expletory
adjective
ex·ple·to·ry ˈek-splə-ˌtȯr-ē 
: expletive
Word History
Etymology
borrowed from New Latin explētōrius "(of a word) filling up or completing," from Latin explēre "to fill up, satisfy, make good" + tōrius, deverbal adjective suffix originally forming derivatives from agent nouns ending in -tōr-, -tor — more at expletive entry 2
First Known Use
1672, in the meaning defined above