Is it ensure, insure, or assure?
(Latin: "striking out"), in prosody, the slurring or omission of a final unstressed vowel that precedes either another vowel or a weak consonant sound, as in the word heav'n. It may also be the dropping of a consonant between vowels, as in the word o'er for over. Elision is used to fit words into a metrical scheme, to smooth the rhythm of a poem, or to ease the pronunciation of words. In classical Greek poetry, an apostrophe (') is substituted for an elided letter, as is frequently the case in English verse. In Latin, however, the elided vowel or consonant remains, but it is ignored in scanning the line