What does "lemon" mean?

Lemon: The tree which bears lemons; the lemon tree. Lemon grass (Bot.), a fragrant East Indian grass (Andropogon Shoenanthus, and perhaps other allied species), which yields the grass oil used in perfumery. -- Lemon sole (Zoöl.), a yellow European sole (Solea aurantiaca). -- Salts of lemon (Chem.), a white crystalline substance, inappropriately named, as it consists of an acid potassium oxalate and contains no citric acid, which is the characteristic acid of lemon; -- called also salis of sorrel. It is used in removing ink stains. See Oxalic acid, under Oxalic. [Colloq.]