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.
Glossary of Grammatical and Rhetorical Terms. Both senses of the term expletive (definitions #1 and #2) are illustrated in these sentences.