ecthlipsis

from The Collaborative International Dictionary of English v.0.48

Ecthlipsis \Ec*thlip"sis\, n. [L., fr. Gr. ?, fr. ? to squeeze
   out.]
   1. The dropping out or suppression from a word of a
      consonant, with or without a vowel.
      [1913 Webster]

   2. (Lat. Pros.) The elision of a final m, with the preceding
      vowel, before a word beginning with a vowel.
      [1913 Webster]