1630s, "pertaining to function or office," from function (n.) + -al (1), or from Medieval Latin functionalis. Meaning "utilitarian" is by 1864; specific use in architecture is from 1928. Related: Functionally; functionality.
a functional set of brakes
a style of writing in which every word is functional
delegates elected on a functional rather than a geographical basis
the toaster was still functional even after being dropped
functional education selects knowledge that is concrete and usable rather than abstract and theoretical