The noun one has 2 senses (first 2 from tagged texts)
1. (44) one, 1, I, ace, single, unity -- (the smallest whole number or a numeral representing this number; "he has the one but will need a two and three to go with it"; "they had lunch at one")
2. (26) one -- (a single person or thing; "he is the best one"; "this is the one I ordered")
Overview of adj one
The adj one has 7 senses (first 5 from tagged texts)
1. (417) one, 1, i, ane -- (used of a single unit or thing; not two or more; "`ane' is Scottish")
2. (4) one, unitary -- (having the indivisible character of a unit; "a unitary action"; "spoke with one voice")
3. (3) one -- (of the same kind or quality; "two animals of one species")
4. (1) one -- (used informally as an intensifier; "that is one fine dog")
5. (1) one -- (indefinite in time or position; "he will come one day"; "one place or another")
6. one -- (being a single entity made by combining separate components; "three chemicals combining into one solution")
7. matchless, nonpareil, one, one and only, peerless, unmatched, unmatchable, unrivaled, unrivalled -- (eminent beyond or above comparison; "matchless beauty"; "the team's nonpareil center fielder"; "she's one girl in a million"; "the one and only Muhammad Ali"; "a peerless scholar"; "infamy unmatched in the Western world"; "wrote with unmatchable clarity"; "unrivaled mastery of her art")