Definition of functional:
designed for or capable of a particular function or use; "a style of writing in which every word is functional"; "functional architecture"
involving or affecting function rather than physiology; "functional deafness"
relating 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"
fit 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"; "the dishwasher is now in working order"
designed for or adapted to a function or use; "functional education selects knowledge that is concrete and usable rather than abstract and theoretical"; "functional architecture"
(of e.g. a machine) performing or capable of performing; "in running (or working) order"; "a functional set of brakes"