'Fibril' definitions:

Definition of 'fibril'

From: WordNet
noun
A very slender natural or synthetic fiber [syn: fibril, filament, strand]

Definition of 'Fibril'

From: GCIDE
  • Fibril \Fi"bril\, n. [F. fibrille, dim. of fibre, L. fibra.] A small fiber; the branch of a fiber; a very slender thread; a fibrilla. --Cheyne. [1913 Webster]