Expletive

a. [Lat. expletivus, Fr. expletif, Pr. expletiu, Sp. & Pg. expletivo, It. espletivo.] Filling up: hence, added merely for the purpose of filling up; superfluous. “Expletive phrases to plump his speech.” Barrow.

n. A word or syllable not necessary to the sense, but inserted to fill a vacancy, or for ornament.

Expletives their feeble aid do join. Pope.