The Collaborative International Dictionary
Synecphonesis
Synecphonesis \Syn*ec`pho*ne"sis\, n. [NL., fr. Gr. ?, fr. ? to utter together.] (Gram.) A contraction of two syllables into one; synizesis.
Wiktionary
synecphonesis
n. (context grammar English) A contraction of two syllables into one; synizesis.