Open English Wordnet
Adjectives
(a)functionaldesigned for or capable of a particular function or use“a style of writing in which every word is functional”, “functional architecture”
(a)functionalrelating to or based on function especially as opposed to structure“the problem now is not a constitutional one: it is a functional one”, “delegates elected on a functional rather than a geographical basis”
(s)functional, usable, useable, operable, operationalfit or ready for use or service“the toaster was still functional even after being dropped”, “the lawnmower is a bit rusty but still usable”, “an operational aircraft”
(s)functionaldesigned for or adapted to a function or use“functional education selects knowledge that is concrete and usable rather than abstract and theoretical”, “functional architecture”
(s)running, operative, functional, working(of e.g. a machine) performing or capable of performing“in running (or working) order”, “a functional set of brakes”