expletive
Pronunciation: /ɪkˈspliːtɪv, ɛk-/
noun

Origin:
late Middle English (as an adjective): from late Latin expletivus, from explere 'fill out', from ex- 'out' + plere 'fill'. The noun sense 'word used merely to fill out a sentence' (early 17th century) was applied specifically to a swear word in the early 19th century