suit someone to a T

Example: “That job suits her to a T.”

Origin: "To a T" is documented from 1693, in James Wright's satire The Humours and Conversations of the Town, and its real origin is genuinely uncertain despite two frequently repeated guesses that don't hold up. A golfer's tee is ruled out on pure chronology — the idiom predates that use of "tee" by centuries — and a builder's T-square is similarly too recent, appearing well after the phrase was already established. The likeliest actual source is an older, now largely forgotten expression, "to a tittle," documented from 1607, where "tittle" meant the smallest conceivable amount or the tiniest mark in writing — a sense that survives today only in the phrase "not one jot or tittle." "To a T," then, most plausibly took just the first letter of "tittle" as its own shorthand, keeping the original sense of exactness down to the smallest possible detail: something suiting a person "to a T" fits with that same precision, matching perfectly in every particular.