A replacement rule deterministically rewrites one phrase as another. Where dictionary terms are hints, replacement rules are absolute.
Find them in Settings → Custom Dictionary → Replacement rules.
Creating one
Heard… — the phrase to match (e.g. am lin)
Write… — what to write instead (e.g. Amlin)
Aa — tick for case-sensitive matching
Add
Leave the replacement blank to delete the matched phrase from the output — useful for a verbal tic you'd rather never see written down.
How they're applied
Whole-word, so a rule for lead won't mangle leader
After cleanup, so the rule always wins
Toggleable — flip the switch on a rule to disable it without deleting it
Rule or dictionary term?
Dictionary term — you want the word heard correctly and spelled consistently. Start here.
Replacement rule — recognition keeps producing a specific wrong string and you want it rewritten every time, no exceptions.