A yellowish citrus fruit.

A semitropical evergreen tree, Citrus limon, that bears such fruits.

A more or less bright shade of yellow associated with lemon fruits.

A lemon shark (Negaprion brevirostris).

(slang) A defective or inadequate item or individual.

(Cockney rhyming slang, shortened from “lemon flavour”) Favor.

(fandom slang) A piece of fanfiction involving explicit sex.

(transitive) To flavour with lemon.

Containing or having the flavour/flavor and/or scent of lemons.

Of the pale yellow colour/color of lemons.

(Cockney rhyming slang, from "lemon tart") Smart; cheeky, vocal.