Meaning

noun perching birds mostly small and living near the ground with feet having 4 toes arranged to allow for gripping the perch; most are songbirds; hatchlings are helpless

adjective relating to or characteristic of the passeriform birds

originAdjective sense 1 is borrowed from New Latin Passer (“bird genus”) (from Latin passer (“sparrow”), ultimately from Proto-Indo-European *peth₂- (“to spread out; to fly (in the sense of spreading out wings)”)) + English -ine (suffix meaning ‘of or pertaining to’). Adjective sense 2 is borrowed from New Latin passerinus (“bird species”) + English -ine. Passerinus is derived from Latin passerīnus…

Etymology from Wiktionary, CC BY-SA 3.0