diff --git a/cli/js/buffer.ts b/cli/js/buffer.ts
index fcb688b9bc..e2a7e3de97 100644
--- a/cli/js/buffer.ts
+++ b/cli/js/buffer.ts
@@ -4,7 +4,7 @@
 // Copyright 2009 The Go Authors. All rights reserved. BSD license.
 // https://github.com/golang/go/blob/master/LICENSE
 
-import { Reader, Writer, EOF, SyncReader, SyncWriter } from "./io.ts";
+import { Reader, Writer, EOF, ReaderSync, WriterSync } from "./io.ts";
 import { assert } from "./util.ts";
 import { TextDecoder } from "./web/text_encoding.ts";
 
@@ -27,7 +27,7 @@ function copyBytes(dst: Uint8Array, src: Uint8Array, off = 0): number {
   return src.byteLength;
 }
 
-export class Buffer implements Reader, SyncReader, Writer, SyncWriter {
+export class Buffer implements Reader, ReaderSync, Writer, WriterSync {
   #buf: Uint8Array; // contents are the bytes buf[off : len(buf)]
   #off = 0; // read at buf[off], write at buf[buf.byteLength]
 
@@ -180,7 +180,7 @@ export class Buffer implements Reader, SyncReader, Writer, SyncWriter {
     }
   }
 
-  readFromSync(r: SyncReader): number {
+  readFromSync(r: ReaderSync): number {
     let n = 0;
     while (true) {
       try {
@@ -206,7 +206,7 @@ export async function readAll(r: Reader): Promise<Uint8Array> {
   return buf.bytes();
 }
 
-export function readAllSync(r: SyncReader): Uint8Array {
+export function readAllSync(r: ReaderSync): Uint8Array {
   const buf = new Buffer();
   buf.readFromSync(r);
   return buf.bytes();
@@ -219,7 +219,7 @@ export async function writeAll(w: Writer, arr: Uint8Array): Promise<void> {
   }
 }
 
-export function writeAllSync(w: SyncWriter, arr: Uint8Array): void {
+export function writeAllSync(w: WriterSync, arr: Uint8Array): void {
   let nwritten = 0;
   while (nwritten < arr.length) {
     nwritten += w.writeSync(arr.subarray(nwritten));
diff --git a/cli/js/deno.ts b/cli/js/deno.ts
index 66ae5e176a..ed4c6d5c37 100644
--- a/cli/js/deno.ts
+++ b/cli/js/deno.ts
@@ -46,9 +46,9 @@ export {
   iterSync,
   SeekMode,
   Reader,
-  SyncReader,
+  ReaderSync,
   Writer,
-  SyncWriter,
+  WriterSync,
   Closer,
   Seeker,
 } from "./io.ts";
diff --git a/cli/js/files.ts b/cli/js/files.ts
index 9b4738ba59..46d6c8a850 100644
--- a/cli/js/files.ts
+++ b/cli/js/files.ts
@@ -6,9 +6,9 @@ import {
   Seeker,
   Closer,
   SeekMode,
-  SyncReader,
-  SyncWriter,
-  SyncSeeker,
+  ReaderSync,
+  WriterSync,
+  SeekerSync,
 } from "./io.ts";
 import { close } from "./ops/resources.ts";
 import { read, readSync, write, writeSync } from "./ops/io.ts";
@@ -60,11 +60,11 @@ export function create(path: string): Promise<File> {
 export class File
   implements
     Reader,
-    SyncReader,
+    ReaderSync,
     Writer,
-    SyncWriter,
+    WriterSync,
     Seeker,
-    SyncSeeker,
+    SeekerSync,
     Closer {
   constructor(readonly rid: number) {}
 
@@ -97,7 +97,7 @@ export class File
   }
 }
 
-class Stdin implements Reader, SyncReader, Closer {
+class Stdin implements Reader, ReaderSync, Closer {
   readonly rid: number;
   constructor() {
     this.rid = 0;
@@ -116,7 +116,7 @@ class Stdin implements Reader, SyncReader, Closer {
   }
 }
 
-class Stdout implements Writer, SyncWriter, Closer {
+class Stdout implements Writer, WriterSync, Closer {
   readonly rid: number;
   constructor() {
     this.rid = 1;
@@ -135,7 +135,7 @@ class Stdout implements Writer, SyncWriter, Closer {
   }
 }
 
-export class Stderr implements Writer, SyncWriter, Closer {
+export class Stderr implements Writer, WriterSync, Closer {
   readonly rid: number;
   constructor() {
     this.rid = 2;
diff --git a/cli/js/io.ts b/cli/js/io.ts
index dace11c45f..0b77206821 100644
--- a/cli/js/io.ts
+++ b/cli/js/io.ts
@@ -22,7 +22,7 @@ export interface Reader {
   read(p: Uint8Array): Promise<number | EOF>;
 }
 
-export interface SyncReader {
+export interface ReaderSync {
   readSync(p: Uint8Array): number | EOF;
 }
 
@@ -32,7 +32,7 @@ export interface Writer {
   write(p: Uint8Array): Promise<number>;
 }
 
-export interface SyncWriter {
+export interface WriterSync {
   writeSync(p: Uint8Array): number;
 }
 
@@ -48,7 +48,7 @@ export interface Seeker {
   seek(offset: number, whence: SeekMode): Promise<number>;
 }
 
-export interface SyncSeeker {
+export interface SeekerSync {
   seekSync(offset: number, whence: SeekMode): number;
 }
 
@@ -93,7 +93,7 @@ export async function* iter(
 }
 
 export function* iterSync(
-  r: SyncReader,
+  r: ReaderSync,
   options?: {
     bufSize?: number;
   }
diff --git a/cli/js/lib.deno.ns.d.ts b/cli/js/lib.deno.ns.d.ts
index d74e4fe3f3..2055baf9b9 100644
--- a/cli/js/lib.deno.ns.d.ts
+++ b/cli/js/lib.deno.ns.d.ts
@@ -395,7 +395,7 @@ declare namespace Deno {
     read(p: Uint8Array): Promise<number | EOF>;
   }
 
-  export interface SyncReader {
+  export interface ReaderSync {
     /** Reads up to `p.byteLength` bytes into `p`. It resolves to the number
      * of bytes read (`0` < `n` <= `p.byteLength`) and rejects if any error
      * encountered. Even if `read()` returns `n` < `p.byteLength`, it may use
@@ -414,7 +414,7 @@ declare namespace Deno {
      *
      * Implementations should not retain a reference to `p`.
      *
-     * Use Deno.iterSync() to turn a SyncReader into an Iterator.
+     * Use Deno.iterSync() to turn a ReaderSync into an Iterator.
      */
     readSync(p: Uint8Array): number | EOF;
   }
@@ -432,7 +432,7 @@ declare namespace Deno {
     write(p: Uint8Array): Promise<number>;
   }
 
-  export interface SyncWriter {
+  export interface WriterSync {
     /** Writes `p.byteLength` bytes from `p` to the underlying data
      * stream. It returns the number of bytes written from `p` (`0` <= `n`
      * <= `p.byteLength`) and any error encountered that caused the write to
@@ -464,7 +464,7 @@ declare namespace Deno {
     seek(offset: number, whence: SeekMode): Promise<number>;
   }
 
-  export interface SyncSeeker {
+  export interface SeekerSync {
     /** Seek sets the offset for the next `readSync()` or `writeSync()` to
      * offset, interpreted according to `whence`: `Start` means relative
      * to the start of the file, `Current` means relative to the current
@@ -533,7 +533,7 @@ declare namespace Deno {
     }
   ): AsyncIterableIterator<Uint8Array>;
 
-  /** Turns a SyncReader, `r`, into an iterator.
+  /** Turns a ReaderSync, `r`, into an iterator.
    *
    *      let f = Deno.openSync("/etc/passwd");
    *      for (const chunk of Deno.iterSync(reader)) {
@@ -559,7 +559,7 @@ declare namespace Deno {
    * next iteration will overwrite contents of previously returned chunk.
    */
   export function iterSync(
-    r: SyncReader,
+    r: ReaderSync,
     options?: {
       bufSize?: number;
     }
@@ -733,11 +733,11 @@ declare namespace Deno {
   export class File
     implements
       Reader,
-      SyncReader,
+      ReaderSync,
       Writer,
-      SyncWriter,
+      WriterSync,
       Seeker,
-      SyncSeeker,
+      SeekerSync,
       Closer {
     readonly rid: number;
     constructor(rid: number);
@@ -751,11 +751,11 @@ declare namespace Deno {
   }
 
   /** A handle for `stdin`. */
-  export const stdin: Reader & SyncReader & Closer & { rid: number };
+  export const stdin: Reader & ReaderSync & Closer & { rid: number };
   /** A handle for `stdout`. */
-  export const stdout: Writer & SyncWriter & Closer & { rid: number };
+  export const stdout: Writer & WriterSync & Closer & { rid: number };
   /** A handle for `stderr`. */
-  export const stderr: Writer & SyncWriter & Closer & { rid: number };
+  export const stderr: Writer & WriterSync & Closer & { rid: number };
 
   export interface OpenOptions {
     /** Sets the option for read access. This option, when `true`, means that the
@@ -831,7 +831,7 @@ declare namespace Deno {
    * of ArrayBuffer.
    *
    * Based on [Go Buffer](https://golang.org/pkg/bytes/#Buffer). */
-  export class Buffer implements Reader, SyncReader, Writer, SyncWriter {
+  export class Buffer implements Reader, ReaderSync, Writer, WriterSync {
     constructor(ab?: ArrayBuffer);
     /** Returns a slice holding the unread portion of the buffer.
      *
@@ -892,7 +892,7 @@ declare namespace Deno {
      *
      * Based on Go Lang's
      * [Buffer.ReadFrom](https://golang.org/pkg/bytes/#Buffer.ReadFrom). */
-    readFromSync(r: SyncReader): number;
+    readFromSync(r: ReaderSync): number;
   }
 
   /** Read Reader `r` until end of file (`Deno.EOF`) and resolve to the content
@@ -931,7 +931,7 @@ declare namespace Deno {
    *       const reader = new Deno.Buffer(myData.buffer as ArrayBuffer);
    *       const bufferContent = Deno.readAllSync(reader);
    */
-  export function readAllSync(r: SyncReader): Uint8Array;
+  export function readAllSync(r: ReaderSync): Uint8Array;
 
   /** Write all the content of the array buffer (`arr`) to the writer (`w`).
    *
@@ -972,7 +972,7 @@ declare namespace Deno {
    *       Deno.writeAllSync(writer, contentBytes);
    *       console.log(writer.bytes().length);  // 11
    */
-  export function writeAllSync(w: SyncWriter, arr: Uint8Array): void;
+  export function writeAllSync(w: WriterSync, arr: Uint8Array): void;
 
   export interface MkdirOptions {
     /** Defaults to `false`. If set to `true`, means that any intermediate
diff --git a/cli/js/tests/files_test.ts b/cli/js/tests/files_test.ts
index 62f044f03a..eda484b2dc 100644
--- a/cli/js/tests/files_test.ts
+++ b/cli/js/tests/files_test.ts
@@ -128,7 +128,7 @@ unitTest(async function readerIterSync(): Promise<void> {
   // ref: https://github.com/denoland/deno/issues/2330
   const encoder = new TextEncoder();
 
-  class TestReader implements Deno.SyncReader {
+  class TestReader implements Deno.ReaderSync {
     #offset = 0;
     #buf: Uint8Array;
 
diff --git a/std/io/bufio.ts b/std/io/bufio.ts
index a4e729cfdf..cd08fbefac 100644
--- a/std/io/bufio.ts
+++ b/std/io/bufio.ts
@@ -5,7 +5,7 @@
 
 type Reader = Deno.Reader;
 type Writer = Deno.Writer;
-type SyncWriter = Deno.SyncWriter;
+type WriterSync = Deno.WriterSync;
 import { charCode, copyBytes } from "./util.ts";
 import { assert } from "../testing/asserts.ts";
 
@@ -524,17 +524,17 @@ export class BufWriter extends AbstractBufBase implements Writer {
   }
 }
 
-/** BufWriterSync implements buffering for a deno.SyncWriter object.
- * If an error occurs writing to a SyncWriter, no more data will be
+/** BufWriterSync implements buffering for a deno.WriterSync object.
+ * If an error occurs writing to a WriterSync, no more data will be
  * accepted and all subsequent writes, and flush(), will return the error.
  * After all data has been written, the client should call the
  * flush() method to guarantee all data has been forwarded to
- * the underlying deno.SyncWriter.
+ * the underlying deno.WriterSync.
  */
-export class BufWriterSync extends AbstractBufBase implements SyncWriter {
+export class BufWriterSync extends AbstractBufBase implements WriterSync {
   /** return new BufWriterSync unless writer is BufWriterSync */
   static create(
-    writer: SyncWriter,
+    writer: WriterSync,
     size: number = DEFAULT_BUF_SIZE
   ): BufWriterSync {
     return writer instanceof BufWriterSync
@@ -542,7 +542,7 @@ export class BufWriterSync extends AbstractBufBase implements SyncWriter {
       : new BufWriterSync(writer, size);
   }
 
-  constructor(private writer: SyncWriter, size: number = DEFAULT_BUF_SIZE) {
+  constructor(private writer: WriterSync, size: number = DEFAULT_BUF_SIZE) {
     super();
     if (size <= 0) {
       size = DEFAULT_BUF_SIZE;
@@ -553,13 +553,13 @@ export class BufWriterSync extends AbstractBufBase implements SyncWriter {
   /** Discards any unflushed buffered data, clears any error, and
    * resets buffer to write its output to w.
    */
-  reset(w: SyncWriter): void {
+  reset(w: WriterSync): void {
     this.err = null;
     this.usedBufferBytes = 0;
     this.writer = w;
   }
 
-  /** Flush writes any buffered data to the underlying io.SyncWriter. */
+  /** Flush writes any buffered data to the underlying io.WriterSync. */
   flush(): void {
     if (this.err !== null) throw this.err;
     if (this.usedBufferBytes === 0) return;