Ex"ple*tive (?), a. [L. expletivus, from expletus, p. p. of explere to fill up; ex out+plere to fill, akin to plenus full: cf. F. explétif. See Full.] Filling up; hence, added merely for the purpose of filling up; superfluous. "Expletive imagery." Hallam.

Expletive phrases to plump his speech.

Ex"ple*tive, n. A word, letter, or syllable not necessary to the sense, but inserted to fill a vacancy; an oath.

While explectives their feeble aid to join,
And ten low words oft creep in one dull line.

• A profane, vulgar or obscene oath
  
• (linguistics) A word without meaning added to fill a syntactic position
       Example: - It in It is snowing
  
• (linguistics) A word that adds to the strength of a phrase without affecting its meaning
       Example: - bloody in I'll give you a bloody good hiding.