elision: The omission of part of a word (typically a letter). Elision most commonly involves replacing a word-ending vowel with an apostrophe when it is followed by another word that begins with a vowel.Ross Murfin and Supryia M. Ray The Bedford Glossary of Critical and Literary Terms
The visual stylistic approach of the elision; I at least thought it was mainly the visual. But the way it works out is far more than simply visual; it is intended to make the words more suited to a metrical pattern.
It is almost a cheating tool. Want to use the word but it doesn't quite fit? No problem! Bring on an elision!