The Collaborative International Dictionary
FibrillAE
Fibrilla \Fi*bril"la\, n.; pl. Fibrill[AE]. [NL. See Fibril.] A minute thread or fiber, as one of the fibrous elements of a muscular fiber; a fibril.
Wiktionary
fibrillae
n. (plural of fibrilla English)
WordNet
fibrillae
See fibrilla