The Collaborative International Dictionary of English v.0.48:
Ectasis \Ec"ta*sis\, n. [L., fr. Gr. ?; 'ek out + ? to stretch.] (Pros.) The lengthening of a syllable from short to long. [1913 Webster]WordNet (r) 3.0 (2006):
ectasis n 1: dilatation or distension of a hollow organ [syn: ectasia, ectasis]