functional.

In good working order.

Useful; serving a purpose, fulfilling a function.

That sculpture is not merely artistic, but also functional: it can be used as a hatrack.

Only for functional purposes, notably in architecture.

A functional construction element generally must meet higher technical but lower aesthetical requirements.

Of or relating to one's role or office; official.

functional responsibilities

Characterizing functioning in environment, being symptoms that do not presuppose alteration of organic structure.

Optimized for all-around physiological benefit.

functional coffee

functional fitness

Of or relating to a function or functions.

Having semantics defined purely in terms of mathematical functions, without side-effects.

A function that takes a function as its argument; more precisely, a function whose argument varies in a space of (real- or complex-valued) functions and whose value belongs to a monodimensional space.

An example of a functional is the definite integration of integrable real functions in a real interval.

A scalar-valued linear function on a vector space.

An object encapsulating a function pointer (or equivalent).