an interjectory word or expression, frequently profane; an exclamatory oath.

a syllable, word, or phrase serving to fill out.

Grammar . a word considered as regularly filling the syntactic position of another, as it in It is his duty to go, or there in There is nothing here.

Also, expletory

noun

curse , cuss , cuss word , interjection , oath , blasphemy , epithet , exclamation , swear