Infantry
late 16th century: from French infanterie, from Italian infanteria, from infante ‘youth, infantryman’, from Latin infant- (see infant).
wiktionary
From Middle French infanterie, from older Italian, possibly from Spanish infantería(“foot soldiers, force composed of those too inexperienced or low in rank for cavalry”), from infante(“foot soldier”), originally "a youth", either way from Latin īnfāns(“child”); see there for more.
etymonline
infantry (n.)
1570s, from French infantrie, infanterie (16c.), from older Italian or Spanish infanteria "foot soldiers, force composed of those too inexperienced or low in rank to be cavalry," a collective noun from infante "foot soldier," originally "a youth," from Latin infantem (see infant). Meaning "infants collectively" is recorded from 1610s. A Middle English (c. 1200) word for "foot-soldiers" was going-folc, literally "going-folk."
