The adjective G. fidhrin “haired” appeared as an element in the word G. logrifidhrin (or logrifindel) “curly haired” from the Gnomish Lexicon of the 1910s (GL/54). It is apparently an elaboration of fidhra “[collective] hair” (GL/35).

Neo-Sindarin: I would adapt this word as ᴺS. fidhren “having hair, -haired” < *spinrinā using the more typical Sindarin adjective suffix S. -ren, where the dhr is the result of the Sindarin sound change whereby [nr] became [ðr]. I think this is better than coining an Sindarin variant of Q. finda “having hair, -haired” (PM/340), since a cognate of that word would collide with S. fen(n) “door”.