Anon: "one-word phrase" is an oxymoron, so impossible to answer your question. "a man of few words" (phrase) laconic (one word)
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An oxymoron is a deliberate device for pointing up a paradox, so "one-word phrase" is not an oxymoron unless one sets it up on purpose to be that.
In any case, there's no such thing as a one-word phrase.