2 senses of elision

Sense 1
elision -- (omission of a sound between two words (usually a vowel and the end of one word or the beginning of the next))

omission, deletion -- (any process whereby sounds or words are left out of spoken words or phrases)

Sense 2
exception, exclusion, elision -- (a deliberate act of omission; ``with the exception of the children, everyone was told the news'' )

omission -- (neglecting to do something; leaving out or passing over something)