ex·ple·tive / ˈeksplitiv/ • n. an oath or swear word. ∎  Gram. a word or phrase used to fill out a sentence or a line of verse without adding to the sense.• adj. Gram. (of a word or phrase) serving to fill out a sentence or line of verse.ORIGIN: late Middle English (as an adjective): from late Latin expletivus, from explere ‘fill out,’ from ex- ‘out’ + plere ‘fill.’ The general noun sense ‘word used merely to fill out a sentence’ (early 17th cent.) was applied specifically to an oath or swear word in the early 19th cent.

EXPLETIVE.
1. Originally, an expression used to fill out a line of verse or a sentence, without adding anything to the sense
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2. An interjected word, especially an oath or swearword. At the time of the Watergate hearings in the US in the 1970s, during the presidency of Richard Nixon, the phrase expletive deleted occurred frequently in the transcript of the White House tapes. See INFIX, SWEARING.

expletive serving to fill out; sb. expletive word. XVII (used of a profane oath, etc. XIX). — late L. explētīvus, f. explēre, f. EX-1 + plēre fill; see FULL, -IVE.