How to Add Custom Words to Your Mac Dictation

If your Mac keeps mangling a coworker's name, a product you sell, or an acronym from your field, you are not doing anything wrong. Dictation guesses from common spellings. The fix is to teach it the words you actually use, and there is a clean way and a clunky way to do that.

Why your Mac gets certain words wrong

Speech recognition is a probability engine. When you say a rare name, the model compares what it heard against millions of common spellings and picks the most likely match. That is why "Ng" becomes "ing", "Kubernetes" becomes "cooper netties", and your startup's clever brand name turns into three ordinary words. The audio was fine. The model simply preferred a more frequent guess.

This gets worse with acronyms, medical and legal terms, and anything in a second language. If you want the deeper mechanics of why local models behave this way, our primer on what on-device speech recognition is walks through how the pipeline turns sound into text. The takeaway for now: to change the output, you need to nudge the model's guess, not fight it after the fact.

Myth versus fact: custom words on a Mac

Option 1: the Apple Dictation workaround

If you want to stay with built-in dictation, Text Replacement is the honest workaround. Open System Settings, go to Keyboard, then Text Replacements, and add a rule. The trick is to pick a trigger that dictation can hear cleanly and that you would never type by accident, then map it to the correct spelling.

• Add the rule. Replace a phrase like "kates surname" with "Kaczmarek".
• Speak the trigger. When you dictate, say the trigger phrase and macOS swaps in the real spelling.
• Sync across devices. Text Replacements ride along with iCloud, so the rule follows you.

It works for a handful of words, but it is fragile. You have to remember every trigger, the substitution can misfire mid-sentence, and it does nothing for accuracy in longer passages. For occasional use it is fine. For daily dictation it becomes a chore.

Option 2: a real custom dictionary

The cleaner approach is a dictation app that ships with a custom dictionary, so you teach the recognizer the word itself instead of patching the output. In BlaBlaType you open the dictionary, add the exact spellings you use, whether that is a client roster, a codebase of function names, or drug names, and they are applied on-device every time you speak. Because the app also runs on-device AI cleanup, filler words and punctuation are fixed in the same pass, so your custom terms land inside already-polished text.

This scales in a way Text Replacement never will. There are no triggers to memorize, the words simply come out right, and it works the same whether you are dictating into email, an editor, or an AI chat. Power users on other platforms lean on scripting tools like Talon to get this kind of control, but on a Mac a built-in dictionary keeps it simple.

Two ways compared

Both keep your data on the Mac, which matters if you care about privacy. The difference is that a dictionary fixes the word at the source, so accuracy improves for the whole sentence, not just the one term. If you regularly switch languages, pairing a dictionary with proper multilingual support helps even more; see our guide to dictating in multiple languages on a Mac.

Getting the most from a custom dictionary

A few habits make custom words far more reliable. Add terms as you hit them rather than in one giant batch, so each addition solves a real miss. Write the spelling exactly as you want it to appear, including capitalization and hyphens. Group related terms, like every name on a project, so a single dictation session comes out clean. And remember that dictation pays off precisely because most people speak around three to four times faster than they type, so any word you fix once saves you edits every day after. If you are weighing that trade-off in general, our piece on dictation versus typing puts numbers to it, drawing on the standard words-per-minute measure.

Custom vocabulary is one of those small features that quietly decides whether you keep dictating or give up. Once your Mac spells your world correctly, voice becomes the faster path for real, and you can see current options on the pricing page.