Definition of modals:
(adj) :
Of, or relating to a mode or modus.
(adj) :
(grammar) Of, relating to, or describing the mood of a clause.
(adj) :
(logic) Of, or relating to the modality between propositions.
(adj) :
(computing) Having separate modes in which user input has different effects.
(n) :
(linguistics) A modal form, notably a modal auxiliary.
(n) :
(grammar) A modal verb.