1) Deletion 2) Especial to special 3) Omission 
loss of initial unaccented vowel from beginning of a word
the omission of the initial syllable of a word. See also Apocope.
• (n.) The loss of a short unaccented vowel at the beginning of a word; -- the result of a phonetic process; as, squire for esquire.
Linguistically, the omission of an unaccented syllable from the front of a word. Contrast with the m
The omission of the initial syllable of a word. See also apocope.
Aph'e·sis noun [ Greek ... a letting go; ... + ... to let go.] The loss of a short unaccented vowel at the beginning of a word; -- the result of a phonetic process; as, squire for esquire . New Eng. Dict. 
The loss of letters or syllables at the start of a word. Opposite of apocope.
[n] - the gradual disappearance of an initial (usually unstressed) vowel or syllable as in `squire` for `esquire`
noun the gradual disappearance of an initial (usually unstressed) vowel or syllable as in `squire` for `esquire`
the disappearance or loss of an unstressed initial vowel or syllable.