Mid 19th century; earliest use found in William Whitney (1827–1894). From Pāṇini, the name of an ancient Indian grammarian (? 400 b.c.), who wrote the sutras on Sanskrit grammar on which much later work was based + -an, after Sanskrit Pāṇinīya of or relating to Pāṇini, Pāṇini's grammar as distinguished from other systems of Sanskrit grammar.