diff --git a/src/Init/Data/BitVec/Basic.lean b/src/Init/Data/BitVec/Basic.lean
index b9ba2423ea..fc3dd94437 100644
--- a/src/Init/Data/BitVec/Basic.lean
+++ b/src/Init/Data/BitVec/Basic.lean
@@ -25,6 +25,10 @@ set_option linter.missingDocs true
 
 namespace BitVec
 
+@[inline, deprecated BitVec.ofNatLT (since := "2025-02-13"), inherit_doc BitVec.ofNatLT]
+protected def ofNatLt {n : Nat} (i : Nat) (p : i < 2 ^ n) : BitVec n :=
+  BitVec.ofNatLT i p
+
 section Nat
 
 instance natCastInst : NatCast (BitVec w) := ⟨BitVec.ofNat w⟩
@@ -55,12 +59,12 @@ end subsingleton
 section zero_allOnes
 
 /-- Return a bitvector `0` of size `n`. This is the bitvector with all zero bits. -/
-protected def zero (n : Nat) : BitVec n := .ofNatLt 0 (Nat.two_pow_pos n)
+protected def zero (n : Nat) : BitVec n := .ofNatLT 0 (Nat.two_pow_pos n)
 instance : Inhabited (BitVec n) where default := .zero n
 
 /-- Bit vector of size `n` where all bits are `1`s -/
 def allOnes (n : Nat) : BitVec n :=
-  .ofNatLt (2^n - 1) (Nat.le_of_eq (Nat.sub_add_cancel (Nat.two_pow_pos n)))
+  .ofNatLT (2^n - 1) (Nat.le_of_eq (Nat.sub_add_cancel (Nat.two_pow_pos n)))
 
 end zero_allOnes
 
@@ -138,7 +142,7 @@ protected def toInt (x : BitVec n) : Int :=
     (x.toNat : Int) - (2^n : Nat)
 
 /-- The `BitVec` with value `(2^n + (i mod 2^n)) mod 2^n`.  -/
-protected def ofInt (n : Nat) (i : Int) : BitVec n := .ofNatLt (i % (Int.ofNat (2^n))).toNat (by
+protected def ofInt (n : Nat) (i : Int) : BitVec n := .ofNatLT (i % (Int.ofNat (2^n))).toNat (by
   apply (Int.toNat_lt _).mpr
   · apply Int.emod_lt_of_pos
     exact Int.ofNat_pos.mpr (Nat.two_pow_pos _)
@@ -167,12 +171,12 @@ recommended_spelling "one" for "1#n" in [BitVec.ofNat, «term__#__»]
   | `($(_) $n $i:num) => `($i:num#$n)
   | _ => throw ()
 
-/-- Notation for bit vector literals without truncation. `i#'lt` is a shorthand for `BitVec.ofNatLt i lt`. -/
+/-- Notation for bit vector literals without truncation. `i#'lt` is a shorthand for `BitVec.ofNatLT i lt`. -/
 scoped syntax:max term:max noWs "#'" noWs term:max : term
-macro_rules | `($i#'$p) => `(BitVec.ofNatLt $i $p)
+macro_rules | `($i#'$p) => `(BitVec.ofNatLT $i $p)
 
 /-- Unexpander for bit vector literals without truncation. -/
-@[app_unexpander BitVec.ofNatLt] def unexpandBitVecOfNatLt : Lean.PrettyPrinter.Unexpander
+@[app_unexpander BitVec.ofNatLT] def unexpandBitVecOfNatLt : Lean.PrettyPrinter.Unexpander
   | `($(_) $i $p) => `($i#'$p)
   | _ => throw ()
 
@@ -356,7 +360,7 @@ end relations
 section cast
 
 /-- `cast eq x` embeds `x` into an equal `BitVec` type. -/
-@[inline] protected def cast (eq : n = m) (x : BitVec n) : BitVec m := .ofNatLt x.toNat (eq ▸ x.isLt)
+@[inline] protected def cast (eq : n = m) (x : BitVec n) : BitVec m := .ofNatLT x.toNat (eq ▸ x.isLt)
 
 @[simp] theorem cast_ofNat {n m : Nat} (h : n = m) (x : Nat) :
     (BitVec.ofNat n x).cast h = BitVec.ofNat m x := by
diff --git a/src/Init/Data/BitVec/Lemmas.lean b/src/Init/Data/BitVec/Lemmas.lean
index fd63753d50..f404dca034 100644
--- a/src/Init/Data/BitVec/Lemmas.lean
+++ b/src/Init/Data/BitVec/Lemmas.lean
@@ -274,16 +274,27 @@ theorem ofBool_eq_iff_eq : ∀ {b b' : Bool}, BitVec.ofBool b = BitVec.ofBool b'
 
 @[simp, bitvec_to_nat] theorem toNat_ofFin (x : Fin (2^n)) : (BitVec.ofFin x).toNat = x.val := rfl
 
-@[simp] theorem toNat_ofNatLt (x : Nat) (p : x < 2^w) : (x#'p).toNat = x := rfl
+@[simp] theorem toNat_ofNatLT (x : Nat) (p : x < 2^w) : (x#'p).toNat = x := rfl
 
-@[simp] theorem getLsbD_ofNatLt {n : Nat} (x : Nat) (lt : x < 2^n) (i : Nat) :
+@[deprecated toNat_ofNatLT (since := "2025-02-13")]
+theorem toNat_ofNatLt (x : Nat) (p : x < 2^w) : (x#'p).toNat = x := rfl
+
+@[simp] theorem getLsbD_ofNatLT {n : Nat} (x : Nat) (lt : x < 2^n) (i : Nat) :
   getLsbD (x#'lt) i = x.testBit i := by
-  simp [getLsbD, BitVec.ofNatLt]
+  simp [getLsbD, BitVec.ofNatLT]
 
-@[simp] theorem getMsbD_ofNatLt {n x i : Nat} (h : x < 2^n) :
+@[deprecated getLsbD_ofNatLT (since := "2025-02-13")]
+theorem getLsbD_ofNatLt {n : Nat} (x : Nat) (lt : x < 2^n) (i : Nat) :
+  getLsbD (x#'lt) i = x.testBit i := getLsbD_ofNatLT x lt i
+
+@[simp] theorem getMsbD_ofNatLT {n x i : Nat} (h : x < 2^n) :
     getMsbD (x#'h) i = (decide (i < n) && x.testBit (n - 1 - i)) := by
   simp [getMsbD, getLsbD]
 
+@[deprecated getMsbD_ofNatLT (since := "2025-02-13")]
+theorem getMsbD_ofNatLt {n x i : Nat} (h : x < 2^n) :
+    getMsbD (x#'h) i = (decide (i < n) && x.testBit (n - 1 - i)) := getMsbD_ofNatLT h
+
 @[simp, bitvec_to_nat] theorem toNat_ofNat (x w : Nat) : (BitVec.ofNat w x).toNat = x % 2^w := by
   simp [BitVec.toNat, BitVec.ofNat, Fin.ofNat']
 
@@ -1217,7 +1228,7 @@ theorem not_def {x : BitVec v} : ~~~x = allOnes v ^^^ x := rfl
 
 @[simp] theorem ofInt_negSucc_eq_not_ofNat {w n : Nat} :
     BitVec.ofInt w (Int.negSucc n) = ~~~.ofNat w n := by
-  simp only [BitVec.ofInt, Int.toNat, Int.ofNat_eq_coe, toNat_eq, toNat_ofNatLt, toNat_not,
+  simp only [BitVec.ofInt, Int.toNat, Int.ofNat_eq_coe, toNat_eq, toNat_ofNatLT, toNat_not,
     toNat_ofNat]
   cases h : Int.negSucc n % ((2 ^ w : Nat) : Int)
   case ofNat =>
@@ -1418,7 +1429,7 @@ theorem shiftLeftZeroExtend_eq {x : BitVec w} :
   apply eq_of_toNat_eq
   rw [shiftLeftZeroExtend, setWidth]
   split
-  · simp only [toNat_ofNatLt, toNat_shiftLeft, toNat_setWidth']
+  · simp only [toNat_ofNatLT, toNat_shiftLeft, toNat_setWidth']
     rw [Nat.mod_eq_of_lt]
     rw [Nat.shiftLeft_eq, Nat.pow_add]
     exact Nat.mul_lt_mul_of_pos_right x.isLt (Nat.two_pow_pos _)
@@ -2901,7 +2912,7 @@ protected theorem ne_of_lt {x y : BitVec n} : x < y → x ≠ y := by
   apply Nat.ne_of_lt
 
 protected theorem umod_lt (x : BitVec n) {y : BitVec n} : 0 < y → x % y < y := by
-  simp only [ofNat_eq_ofNat, lt_def, toNat_ofNat, Nat.zero_mod, umod, toNat_ofNatLt]
+  simp only [ofNat_eq_ofNat, lt_def, toNat_ofNat, Nat.zero_mod, umod, toNat_ofNatLT]
   apply Nat.mod_lt
 
 theorem not_lt_iff_le {x y : BitVec w} : (¬ x < y) ↔ y ≤ x := by
@@ -3243,7 +3254,7 @@ theorem toNat_smod {x y : BitVec w} : (x.smod y).toNat =
   by_cases h : x.msb <;> by_cases h' : y.msb
   <;> by_cases h'' : (-x).umod y = 0#w <;> by_cases h''' : x.umod (-y) = 0#w
   <;> simp only [h, h', h'', h''']
-  <;> simp only [umod, toNat_eq, toNat_ofNatLt, toNat_ofNat, Nat.zero_mod] at h'' h'''
+  <;> simp only [umod, toNat_eq, toNat_ofNatLT, toNat_ofNat, Nat.zero_mod] at h'' h'''
   <;> simp [h'', h''']
 
 @[simp]
diff --git a/src/Init/Data/UInt/BasicAux.lean b/src/Init/Data/UInt/BasicAux.lean
index 674f0888dd..eedde3b8f7 100644
--- a/src/Init/Data/UInt/BasicAux.lean
+++ b/src/Init/Data/UInt/BasicAux.lean
@@ -51,7 +51,7 @@ def UInt32.val (x : UInt32) : Fin UInt32.size := x.toFin
 @[extern "lean_uint32_of_nat"]
 def UInt32.ofNat (n : @& Nat) : UInt32 := ⟨BitVec.ofNat 32 n⟩
 @[extern "lean_uint32_of_nat"]
-def UInt32.ofNat' (n : Nat) (h : n < UInt32.size) : UInt32 := ⟨BitVec.ofNatLt n h⟩
+def UInt32.ofNat' (n : Nat) (h : n < UInt32.size) : UInt32 := ⟨BitVec.ofNatLT n h⟩
 /--
 Converts the given natural number to `UInt32`, but returns `2^32 - 1` for natural numbers `>= 2^32`.
 -/
@@ -74,12 +74,12 @@ instance UInt32.instOfNat : OfNat UInt32 n := ⟨UInt32.ofNat n⟩
 
 theorem UInt32.ofNat'_lt_of_lt {n m : Nat} (h1 : n < UInt32.size) (h2 : m < UInt32.size) :
      n < m → UInt32.ofNat' n h1 < UInt32.ofNat m := by
-  simp only [(· < ·), BitVec.toNat, ofNat', BitVec.ofNatLt, ofNat, BitVec.ofNat, Fin.ofNat',
+  simp only [(· < ·), BitVec.toNat, ofNat', BitVec.ofNatLT, ofNat, BitVec.ofNat, Fin.ofNat',
     Nat.mod_eq_of_lt h2, imp_self]
 
 theorem UInt32.lt_ofNat'_of_lt {n m : Nat} (h1 : n < UInt32.size) (h2 : m < UInt32.size) :
      m < n → UInt32.ofNat m < UInt32.ofNat' n h1  := by
-  simp only [(· < ·), BitVec.toNat, ofNat', BitVec.ofNatLt, ofNat, BitVec.ofNat, Fin.ofNat',
+  simp only [(· < ·), BitVec.toNat, ofNat', BitVec.ofNatLT, ofNat, BitVec.ofNat, Fin.ofNat',
     Nat.mod_eq_of_lt h2, imp_self]
 
 /-- Converts a `UInt64` into the corresponding `Fin UInt64.size`. -/
diff --git a/src/Init/Data/UInt/Lemmas.lean b/src/Init/Data/UInt/Lemmas.lean
index 79337988c6..9761d18583 100644
--- a/src/Init/Data/UInt/Lemmas.lean
+++ b/src/Init/Data/UInt/Lemmas.lean
@@ -29,7 +29,7 @@ macro "declare_uint_theorems" typeName:ident bits:term:arg : command => do
 
   @[simp] theorem toNat_ofNat {n : Nat} : (ofNat n).toNat = n % 2 ^ $bits := BitVec.toNat_ofNat ..
 
-  @[simp] theorem toNat_ofNatCore {n : Nat} {h : n < size} : (ofNatCore n h).toNat = n := BitVec.toNat_ofNatLt ..
+  @[simp] theorem toNat_ofNatCore {n : Nat} {h : n < size} : (ofNatCore n h).toNat = n := BitVec.toNat_ofNatLT ..
 
   @[simp] theorem toFin_val_eq_toNat (x : $typeName) : x.toFin.val = x.toNat := rfl
   @[deprecated toFin_val_eq_toNat (since := "2025-02-12")]
diff --git a/src/Init/Prelude.lean b/src/Init/Prelude.lean
index ae50301480..653e740e5a 100644
--- a/src/Init/Prelude.lean
+++ b/src/Init/Prelude.lean
@@ -1904,7 +1904,7 @@ instance : DecidableEq (BitVec n) := BitVec.decEq
 
 /-- The `BitVec` with value `i`, given a proof that `i < 2^n`. -/
 @[match_pattern]
-protected def BitVec.ofNatLt {n : Nat} (i : Nat) (p : LT.lt i (hPow 2 n)) : BitVec n where
+protected def BitVec.ofNatLT {n : Nat} (i : Nat) (p : LT.lt i (hPow 2 n)) : BitVec n where
   toFin := ⟨i, p⟩
 
 /-- Given a bitvector `x`, return the underlying `Nat`. This is O(1) because `BitVec` is a
@@ -1945,7 +1945,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint8_of_nat"]
 def UInt8.ofNatCore (n : @& Nat) (h : LT.lt n UInt8.size) : UInt8 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 /--
 Pack a `Nat` less than `2^8` into a `UInt8`.
@@ -1953,7 +1953,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint8_of_nat"]
 def UInt8.ofNatLT (n : @& Nat) (h : LT.lt n UInt8.size) : UInt8 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -1999,7 +1999,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint16_of_nat"]
 def UInt16.ofNatCore (n : @& Nat) (h : LT.lt n UInt16.size) : UInt16 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 /--
 Pack a `Nat` less than `2^16` into a `UInt16`.
@@ -2007,7 +2007,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint16_of_nat"]
 def UInt16.ofNatLT (n : @& Nat) (h : LT.lt n UInt16.size) : UInt16 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -2053,7 +2053,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_of_nat"]
 def UInt32.ofNatCore (n : @& Nat) (h : LT.lt n UInt32.size) : UInt32 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 /--
 Pack a `Nat` less than `2^32` into a `UInt32`.
@@ -2061,7 +2061,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_of_nat"]
 def UInt32.ofNatLT (n : @& Nat) (h : LT.lt n UInt32.size) : UInt32 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 /--
 Unpack a `UInt32` as a `Nat`.
@@ -2138,7 +2138,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint64_of_nat"]
 def UInt64.ofNatCore (n : @& Nat) (h : LT.lt n UInt64.size) : UInt64 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 /--
 Pack a `Nat` less than `2^64` into a `UInt64`.
@@ -2146,7 +2146,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint64_of_nat"]
 def UInt64.ofNatLT (n : @& Nat) (h : LT.lt n UInt64.size) : UInt64 where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -2208,7 +2208,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_usize_of_nat"]
 def USize.ofNatCore (n : @& Nat) (h : LT.lt n USize.size) : USize where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 /--
 Pack a `Nat` less than `USize.size` into a `USize`.
@@ -2216,7 +2216,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_usize_of_nat"]
 def USize.ofNatLT (n : @& Nat) (h : LT.lt n USize.size) : USize where
-  toBitVec := BitVec.ofNatLt n h
+  toBitVec := BitVec.ofNatLT n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -2269,7 +2269,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_of_nat"]
 def Char.ofNatAux (n : @& Nat) (h : n.isValidChar) : Char :=
-  { val := ⟨BitVec.ofNatLt n (isValidChar_UInt32 h)⟩, valid := h }
+  { val := ⟨BitVec.ofNatLT n (isValidChar_UInt32 h)⟩, valid := h }
 
 /--
 Convert a `Nat` into a `Char`. If the `Nat` does not encode a valid unicode scalar value,
@@ -2279,7 +2279,7 @@ Convert a `Nat` into a `Char`. If the `Nat` does not encode a valid unicode scal
 def Char.ofNat (n : Nat) : Char :=
   dite (n.isValidChar)
     (fun h => Char.ofNatAux n h)
-    (fun _ => { val := ⟨BitVec.ofNatLt 0 (of_decide_eq_true rfl)⟩, valid := Or.inl (of_decide_eq_true rfl) })
+    (fun _ => { val := ⟨BitVec.ofNatLT 0 (of_decide_eq_true rfl)⟩, valid := Or.inl (of_decide_eq_true rfl) })
 
 theorem Char.eq_of_val_eq : ∀ {c d : Char}, Eq c.val d.val → Eq c d
   | ⟨_, _⟩, ⟨_, _⟩, rfl => rfl
diff --git a/src/Lean/Meta/LitValues.lean b/src/Lean/Meta/LitValues.lean
index 3f28b22949..b3459251ba 100644
--- a/src/Lean/Meta/LitValues.lean
+++ b/src/Lean/Meta/LitValues.lean
@@ -74,7 +74,7 @@ def getFinValue? (e : Expr) : MetaM (Option ((n : Nat) × Fin n)) := OptionT.run
 Return `some ⟨n, v⟩` if `e` is:
 - an `OfNat.ofNat` application
 - a `BitVec.ofNat` application
-- a `BitVec.ofNatLt` application
+- a `BitVec.ofNatLT` application
 that encode a `BitVec n` with value `v`.
 -/
 def getBitVecValue? (e : Expr) : MetaM (Option ((n : Nat) × BitVec n)) := OptionT.run do
@@ -83,7 +83,7 @@ def getBitVecValue? (e : Expr) : MetaM (Option ((n : Nat) × BitVec n)) := Optio
     let n ← getNatValue? nExpr
     let v ← getNatValue? vExpr
     return ⟨n, BitVec.ofNat n v⟩
-  | BitVec.ofNatLt nExpr vExpr _ =>
+  | BitVec.ofNatLT nExpr vExpr _ =>
     let n ← getNatValue? nExpr
     let v ← getNatValue? vExpr
     return ⟨n, BitVec.ofNat n v⟩
diff --git a/src/Std/Tactic/BVDecide/Normalize/BitVec.lean b/src/Std/Tactic/BVDecide/Normalize/BitVec.lean
index ddabc543df..ffd3eb21c8 100644
--- a/src/Std/Tactic/BVDecide/Normalize/BitVec.lean
+++ b/src/Std/Tactic/BVDecide/Normalize/BitVec.lean
@@ -57,8 +57,8 @@ theorem BitVec.sle_eq_ult (x y : BitVec w) :
 attribute [bv_normalize] BitVec.ofNat_eq_ofNat
 
 @[bv_normalize]
-theorem BitVec.ofNatLt_reduce (n : Nat) (h) : BitVec.ofNatLt n h = BitVec.ofNat w n := by
-  simp [BitVec.ofNatLt, BitVec.ofNat, Fin.ofNat', Nat.mod_eq_of_lt h]
+theorem BitVec.ofNatLT_reduce (n : Nat) (h) : BitVec.ofNatLT n h = BitVec.ofNat w n := by
+  simp [BitVec.ofNatLT, BitVec.ofNat, Fin.ofNat', Nat.mod_eq_of_lt h]
 
 @[bv_normalize]
 theorem BitVec.ofBool_eq_if (b : Bool) : BitVec.ofBool b = bif b then 1#1 else 0#1 := by