diff --git a/.cspell.json b/.cspell.json
index ef9daa60d4..8cd83748b4 100644
--- a/.cspell.json
+++ b/.cspell.json
@@ -36,6 +36,7 @@
     "memmap",
     "Manually",
     "rustc",
+    "splitn",
     "unistd",
     "unic",
     // Python
diff --git a/common/src/cformat.rs b/common/src/cformat.rs
index 2c1eda5c4a..524f93de24 100644
--- a/common/src/cformat.rs
+++ b/common/src/cformat.rs
@@ -46,7 +46,7 @@ impl fmt::Display for CFormatError {
     }
 }
 
-pub type CFormatPreconversor = super::format::FormatPreconversor;
+pub type CFormatConversion = super::format::FormatConversion;
 
 #[derive(Debug, PartialEq)]
 pub enum CFormatCase {
@@ -73,7 +73,7 @@ pub enum CFormatType {
     Number(CNumberType),
     Float(CFloatType),
     Character,
-    String(CFormatPreconversor),
+    String(CFormatConversion),
 }
 
 #[derive(Debug, PartialEq)]
@@ -503,10 +503,10 @@ where
         'g' => CFormatType::Float(General(Lowercase)),
         'G' => CFormatType::Float(General(Uppercase)),
         'c' => CFormatType::Character,
-        'r' => CFormatType::String(CFormatPreconversor::Repr),
-        's' => CFormatType::String(CFormatPreconversor::Str),
-        'b' => CFormatType::String(CFormatPreconversor::Bytes),
-        'a' => CFormatType::String(CFormatPreconversor::Ascii),
+        'r' => CFormatType::String(CFormatConversion::Repr),
+        's' => CFormatType::String(CFormatConversion::Str),
+        'b' => CFormatType::String(CFormatConversion::Bytes),
+        'a' => CFormatType::String(CFormatConversion::Ascii),
         _ => return Err((CFormatErrorType::UnsupportedFormatChar(c), index)),
     };
     Ok((format_type, c))
@@ -1031,7 +1031,7 @@ mod tests {
                 (
                     18,
                     CFormatPart::Spec(CFormatSpec {
-                        format_type: CFormatType::String(CFormatPreconversor::Str),
+                        format_type: CFormatType::String(CFormatConversion::Str),
                         format_char: 's',
                         mapping_key: None,
                         min_field_width: None,
diff --git a/common/src/format.rs b/common/src/format.rs
index bf3a238b01..ca994c6dbe 100644
--- a/common/src/format.rs
+++ b/common/src/format.rs
@@ -12,43 +12,43 @@ trait FormatParse {
 }
 
 #[derive(Debug, Copy, Clone, PartialEq)]
-pub enum FormatPreconversor {
+pub enum FormatConversion {
     Str,
     Repr,
     Ascii,
     Bytes,
 }
 
-impl FormatParse for FormatPreconversor {
+impl FormatParse for FormatConversion {
     fn parse(text: &str) -> (Option<Self>, &str) {
-        let Some(preconversor) = Self::from_string(text) else {
+        let Some(conversion) = Self::from_string(text) else {
             return (None, text);
         };
         let mut chars = text.chars();
         chars.next(); // Consume the bang
         chars.next(); // Consume one r,s,a char
-        (Some(preconversor), chars.as_str())
+        (Some(conversion), chars.as_str())
     }
 }
 
-impl FormatPreconversor {
-    pub fn from_char(c: char) -> Option<FormatPreconversor> {
+impl FormatConversion {
+    pub fn from_char(c: char) -> Option<FormatConversion> {
         match c {
-            's' => Some(FormatPreconversor::Str),
-            'r' => Some(FormatPreconversor::Repr),
-            'a' => Some(FormatPreconversor::Ascii),
-            'b' => Some(FormatPreconversor::Bytes),
+            's' => Some(FormatConversion::Str),
+            'r' => Some(FormatConversion::Repr),
+            'a' => Some(FormatConversion::Ascii),
+            'b' => Some(FormatConversion::Bytes),
             _ => None,
         }
     }
 
-    fn from_string(text: &str) -> Option<FormatPreconversor> {
+    fn from_string(text: &str) -> Option<FormatConversion> {
         let mut chars = text.chars();
         if chars.next() != Some('!') {
             return None;
         }
 
-        FormatPreconversor::from_char(chars.next()?)
+        FormatConversion::from_char(chars.next()?)
     }
 }
 
@@ -182,7 +182,7 @@ impl FormatParse for FormatType {
 
 #[derive(Debug, PartialEq)]
 pub struct FormatSpec {
-    preconversor: Option<FormatPreconversor>,
+    conversion: Option<FormatConversion>,
     fill: Option<char>,
     align: Option<FormatAlign>,
     sign: Option<FormatSign>,
@@ -270,7 +270,7 @@ fn parse_precision(text: &str) -> Result<(Option<usize>, &str), FormatSpecError>
 impl FormatSpec {
     pub fn parse(text: &str) -> Result<Self, FormatSpecError> {
         // get_integer in CPython
-        let (preconversor, text) = FormatPreconversor::parse(text);
+        let (conversion, text) = FormatConversion::parse(text);
         let (mut fill, mut align, text) = parse_fill_and_align(text);
         let (sign, text) = FormatSign::parse(text);
         let (alternate_form, text) = parse_alternate_form(text);
@@ -289,7 +289,7 @@ impl FormatSpec {
         }
 
         Ok(FormatSpec {
-            preconversor,
+            conversion,
             fill,
             align,
             sign,
@@ -752,7 +752,7 @@ impl FieldName {
 pub enum FormatPart {
     Field {
         field_name: String,
-        preconversion_spec: Option<char>,
+        conversion_spec: Option<char>,
         format_spec: String,
     },
     Literal(String),
@@ -813,12 +813,12 @@ impl FormatString {
             String::new()
         };
 
-        // On parts[0] can still be the preconversor (!r, !s, !a)
+        // On parts[0] can still be the conversion (!r, !s, !a)
         let parts: Vec<&str> = arg_part.splitn(2, '!').collect();
-        // before the bang is a keyword or arg index, after the comma is maybe a conversor spec.
+        // before the bang is a keyword or arg index, after the comma is maybe a conversion spec.
         let arg_part = parts[0];
 
-        let preconversion_spec = parts
+        let conversion_spec = parts
             .get(1)
             .map(|conversion| {
                 // conversions are only every one character
@@ -831,7 +831,7 @@ impl FormatString {
 
         Ok(FormatPart::Field {
             field_name: arg_part.to_owned(),
-            preconversion_spec,
+            conversion_spec,
             format_spec,
         })
     }
@@ -936,7 +936,7 @@ mod tests {
     #[test]
     fn test_width_only() {
         let expected = Ok(FormatSpec {
-            preconversor: None,
+            conversion: None,
             fill: None,
             align: None,
             sign: None,
@@ -952,7 +952,7 @@ mod tests {
     #[test]
     fn test_fill_and_width() {
         let expected = Ok(FormatSpec {
-            preconversor: None,
+            conversion: None,
             fill: Some('<'),
             align: Some(FormatAlign::Right),
             sign: None,
@@ -968,7 +968,7 @@ mod tests {
     #[test]
     fn test_all() {
         let expected = Ok(FormatSpec {
-            preconversor: None,
+            conversion: None,
             fill: Some('<'),
             align: Some(FormatAlign::Right),
             sign: Some(FormatSign::Minus),
@@ -1034,13 +1034,13 @@ mod tests {
                 FormatPart::Literal("abcd".to_owned()),
                 FormatPart::Field {
                     field_name: "1".to_owned(),
-                    preconversion_spec: None,
+                    conversion_spec: None,
                     format_spec: String::new(),
                 },
                 FormatPart::Literal(":".to_owned()),
                 FormatPart::Field {
                     field_name: "key".to_owned(),
-                    preconversion_spec: None,
+                    conversion_spec: None,
                     format_spec: String::new(),
                 },
             ],
@@ -1069,7 +1069,7 @@ mod tests {
                 FormatPart::Literal("{".to_owned()),
                 FormatPart::Field {
                     field_name: "key".to_owned(),
-                    preconversion_spec: None,
+                    conversion_spec: None,
                     format_spec: String::new(),
                 },
                 FormatPart::Literal("}ddfe".to_owned()),
diff --git a/vm/src/cformat.rs b/vm/src/cformat.rs
index 3148975a80..998ac6744e 100644
--- a/vm/src/cformat.rs
+++ b/vm/src/cformat.rs
@@ -21,14 +21,14 @@ fn spec_format_bytes(
     obj: PyObjectRef,
 ) -> PyResult<Vec<u8>> {
     match &spec.format_type {
-        CFormatType::String(preconversor) => match preconversor {
+        CFormatType::String(conversion) => match conversion {
             // Unlike strings, %r and %a are identical for bytes: the behaviour corresponds to
             // %a for strings (not %r)
-            CFormatPreconversor::Repr | CFormatPreconversor::Ascii => {
+            CFormatConversion::Repr | CFormatConversion::Ascii => {
                 let b = builtins::ascii(obj, vm)?.into();
                 Ok(b)
             }
-            CFormatPreconversor::Str | CFormatPreconversor::Bytes => {
+            CFormatConversion::Str | CFormatConversion::Bytes => {
                 if let Ok(buffer) = PyBuffer::try_from_borrowed_object(vm, &obj) {
                     Ok(buffer.contiguous_or_collect(|bytes| spec.format_bytes(bytes)))
                 } else {
@@ -127,12 +127,12 @@ fn spec_format_string(
     idx: &usize,
 ) -> PyResult<String> {
     match &spec.format_type {
-        CFormatType::String(preconversor) => {
-            let result = match preconversor {
-                CFormatPreconversor::Ascii => builtins::ascii(obj, vm)?.into(),
-                CFormatPreconversor::Str => obj.str(vm)?.as_str().to_owned(),
-                CFormatPreconversor::Repr => obj.repr(vm)?.as_str().to_owned(),
-                CFormatPreconversor::Bytes => {
+        CFormatType::String(conversion) => {
+            let result = match conversion {
+                CFormatConversion::Ascii => builtins::ascii(obj, vm)?.into(),
+                CFormatConversion::Str => obj.str(vm)?.as_str().to_owned(),
+                CFormatConversion::Repr => obj.repr(vm)?.as_str().to_owned(),
+                CFormatConversion::Bytes => {
                     // idx is the position of the %, we want the position of the b
                     return Err(vm.new_value_error(format!(
                         "unsupported format character 'b' (0x62) at index {}",
diff --git a/vm/src/format.rs b/vm/src/format.rs
index d13dbd9384..7b11d16dc5 100644
--- a/vm/src/format.rs
+++ b/vm/src/format.rs
@@ -68,7 +68,7 @@ fn format_internal(
         let result_string: &str = match part {
             FormatPart::Field {
                 field_name,
-                preconversion_spec,
+                conversion_spec,
                 format_spec,
             } => {
                 let FieldName { field_type, parts } =
@@ -94,7 +94,7 @@ fn format_internal(
                     FormatString::from_str(format_spec).map_err(|e| e.to_pyexception(vm))?;
                 let format_spec = format_internal(vm, &nested_format, field_func)?;
 
-                pystr = call_object_format(vm, argument, *preconversion_spec, &format_spec)?;
+                pystr = call_object_format(vm, argument, *conversion_spec, &format_spec)?;
                 pystr.as_ref()
             }
             FormatPart::Literal(literal) => literal,
@@ -162,14 +162,14 @@ pub(crate) fn format_map(
 pub fn call_object_format(
     vm: &VirtualMachine,
     argument: PyObjectRef,
-    preconversion_spec: Option<char>,
+    conversion_spec: Option<char>,
     format_spec: &str,
 ) -> PyResult<PyStrRef> {
-    let argument = match preconversion_spec.and_then(FormatPreconversor::from_char) {
-        Some(FormatPreconversor::Str) => argument.str(vm)?.into(),
-        Some(FormatPreconversor::Repr) => argument.repr(vm)?.into(),
-        Some(FormatPreconversor::Ascii) => vm.ctx.new_str(builtins::ascii(argument, vm)?).into(),
-        Some(FormatPreconversor::Bytes) => {
+    let argument = match conversion_spec.and_then(FormatConversion::from_char) {
+        Some(FormatConversion::Str) => argument.str(vm)?.into(),
+        Some(FormatConversion::Repr) => argument.repr(vm)?.into(),
+        Some(FormatConversion::Ascii) => vm.ctx.new_str(builtins::ascii(argument, vm)?).into(),
+        Some(FormatConversion::Bytes) => {
             vm.call_method(&argument, identifier!(vm, decode).as_str(), ())?
         }
         None => argument,
diff --git a/vm/src/stdlib/string.rs b/vm/src/stdlib/string.rs
index e33eca8fb1..4666d83812 100644
--- a/vm/src/stdlib/string.rs
+++ b/vm/src/stdlib/string.rs
@@ -21,14 +21,14 @@ mod _string {
         literal: String,
         field_name: Option<String>,
         format_spec: Option<String>,
-        preconversion_spec: Option<char>,
+        conversion_spec: Option<char>,
         vm: &VirtualMachine,
     ) -> PyObjectRef {
         let tuple = (
             literal,
             field_name,
             format_spec,
-            preconversion_spec.map(|c| c.to_string()),
+            conversion_spec.map(|c| c.to_string()),
         );
         tuple.to_pyobject(vm)
     }
@@ -44,14 +44,14 @@ mod _string {
             match part {
                 FormatPart::Field {
                     field_name,
-                    preconversion_spec,
+                    conversion_spec,
                     format_spec,
                 } => {
                     result.push(create_format_part(
                         mem::take(&mut literal),
                         Some(field_name),
                         Some(format_spec),
-                        preconversion_spec,
+                        conversion_spec,
                         vm,
                     ));
                 }