Source : Webster's Revised Unabridged Dictionary (1913)

Ectasis \Ec"ta*sis\, n. [L., fr. Gr. ?; ? out + ? to stretch.]
   (Pros.)
   The lengthening of a syllable from short to long.

Source : WordNet®

ectasis
     n : dilatation or distension of a hollow organ [syn: {ectasia}]