Definition of functionals:
(adj) :
Useful; serving a purpose, fulfilling a function.
(adj) :
In good working order.
(adj) :
Only for functional purposes, notably in architecture.
(adj) :
Of or relating to one's role or office; official.
(adj) :
(physiology, psychology) Characterizing functioning in environment, being symptoms that do not presuppose alteration of organic structure.
(adj) :
Optimized for all-around physiological benefit.