ex·ple·tive 
(ĕksplĭ-tĭv)
(ĕksplĭ-tĭv)n.
1. An exclamation or oath, especially one that is profane, vulgar, or obscene.
2.
a. A word or phrase that does not contribute any meaning but is added only to fill out a sentence or a metrical line.
b. Linguistics A word or other grammatical element that has no meaning but is needed to fill a syntactic position, such as the words it and there in the sentences It's raining and There are many books on the table.
adj.
Added or inserted in order to fill out something, such as a sentence or a metrical line.
[From Late Latin explētīvus, serving to fill out, from Latin explētus, past participle of explēre, to fill out : ex-, ex- + plēre, to fill; see pelə-1 in the Appendix of Indo-European roots.]