No more than; no one or nothing except; or single in its kind.
From Old English "ānlic" meaning "single, unique," from "ān" (one) and "-lic" (like). It originally meant "one-like" or "alone in its kind."
The link between "only" and "one" is built right into the word: it’s literally "one-like." That’s why "only" can feel limiting ("only one") or special ("the only one"), depending on how you look at it.
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