The Collaborative International Dictionary of English v.0.48:

Filamentary \Fil`a*men"ta*ry\, a.
   Having the character of, or formed by, a filament.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "filamentary":
   bristlelike, capillary, cirrose, cirrous, fibered, fibroid,
   fibrous, flagelliform, flossy, funicular, gossamery, hairlike,
   hairy, ligamental, ropy, silky, stringy, taeniate, taeniform,
   threadlike, thready, wiry