An expletive is a rude word or expression such as `Damn!' which you say when you are annoyed, excited, or in pain. = swear word. a rude word that you use when you are angry or in pain, for example 'shit' = swear word (expletivus, from explere ; because the words fill a space in a sentence without adding to the meaning)
A word, letter, or syllable not necessary to the sense, but inserted to fill a vacancy; an oath
a word or phrase conveying no independent meaning but added to fill out a sentence or metrical line
() From Late Latin explētīvus (“serving to fill out”), from Latin explētus, the perfect passive participle of expleō (“fill out”), itself from ex (“out, completely”) + *pleō (“fill”).