| Neurilemma 1. (n.) The delicate outer sheath of a nerve fiber; the primitive sheath. 2. (n.) The perineurium. Thesaurus Entries allantoic membrane, amniotic sac, arachnoid membrane, basement membrane, conjuctiva, eardrum, hymen, maidenhead, membrana serosa, membrana tympana, membrane, meninges, meninx, neurilemma, pellicle, pericardium, perineurium, pleura, serosa, tympanic membrane, tympanum, velum |