Definition of volatile for English Language Learners. : 1  likely to change in a very sudden or extreme way. : 2  having or showing extreme or sudden changes of emotion. : 3  likely to become dangerous or out of control.
expletive (plural expletives) 1  A profane, vulgar term, notably a curse or obscene oath. ( 2 linguistics) A word without meaning added to fill a syntactic position. ( 3 linguistics) A word that adds to the strength of a phrase without affecting its meaning; an intensifier.
By Richard Nordquist. Definition: (1) In grammar, a construction that begins with the word here, there, or it and is followed by a form of the verb to be. Sometimes called a syntactic expletive. Also see: 1  Cleft. 2  Delayed Subject. 3  Dummy It. 4  Dummy Word. 5  Existential Sentence. 6  Existential There.