Definition from Wiktionary, the free dictionary
räptulav (plural räptulavs)
- reptiliology (science of reptiles), the branch of herpetology (i.e. combined sciences of amphibiology and reptiliology) devoted to the exclusive study of reptiles (Reptilia), See the old online book (New Voyages and Travels. Vol. III (Printed for Sir Richard Phillips and Co.). 1820, p. 84) where the term "reptiliologists" is used.
- Marcgraf mentions this serpent under the Curucucu; but in latter times, Counsellor Merrem, one of our most celebrated Reptiliologists, in the first book of the Annals of the Watterauon Society [i.e. Wetterauische Gesellschaft], for Natural History, has described and sketched an imperfect skin of this creature. 
declension of räptulav