[prahl-tril-er] 
| a melodic embellishment consisting of a rapid alternation of a principal tone with an auxiliary tone one degree above it. |
| prall·tril·ler (präl'trĭl'ər) n. A trill consisting of alternation between a written note and the note immediately above it. Also called inverted mordent. [German : prallen, to rebound (alteration of Middle High German prellen) + Triller, trill (from Italian trillo, from trillare, to trill, probably of imitative origin).] |