functional Adjective Useful; serving a purpose, fulfilling a function
functional Adjective Only for functional purposes, notably in architecture
functional Adjective Having semantics defined purely in terms of mathematical functions, without side-effects.
functional Adjective Of a disease, such that its symptoms cannot be referred to any appreciable lesion or change of structure; opposed to organic disease, in which the organ itself is affected.
functional Noun A function that takes a function as its argument; More precisely: A function "y"="f"("x") whose argument "x" varies in a space of (real valued, complex valued) functions and whose value belongs to a monodimensional space. An example: the definite integration of integrable real functions in a real interval.
functional Noun An object encapsulating a function pointer (or equivalent).