D defs.my
Entry 5 senses Webster, 1913

Functional

/(fŭṉk"shŭn*al)/ · Func·tion·al · IPA /ˈfʌŋkt͡ʃənəl/
01 a. Pertaining to, or connected with, a function or duty; official.
  1. 1.
    Pertaining to, or connected with, a function or duty; official.
  2. 2.
    Pertaining to the function of an organ or part, or to the functions in general; involving or affecting function rather than physiology; as, functional deafness; a functional disease. See functional disease, below.(Pathology, Physiol.)
  3. 3.
    Designed for or capable of a particular function or use; as, a style of writing in which every word is functional; functional architecture.
  4. 4.
    Fit or ready for use or service; useable; in working order; as, the toaster was still functional even after being dropped; the lawnmower is a bit rusty but still functional. Antonym of out of order and nonfunctional.
  5. 5.
    Designed to emphasize practical utility rather than artistic or aesthetic purposes; as, functional education selects knowledge that is concrete and usable rather than abstract and theoretical; functional architecture; an amateurish device, crude but functional.
Phrases & compounds
Functional disease — a disease of which the symptoms cannot be referred to any appreciable lesion or change of structure; the derangement of an organ arising from a cause, often unknown, external to itself opposed to organic disease, in which the organ itself is affected.