Meaning

noun a garment size for a large person

adjective above average in size or number or quantity or magnitude or extent

adjective fairly large or important in effect; influential

originFrom Middle English large, from Old French large, from Latin larga, feminine of largus (“abundant, plentiful, copious, large, much”), of uncertain ultimate origin; see there for more. Along with big, it mostly displaced Middle English stoor and muchel (the latter surviving in much under a different meaning).

Etymology from Wiktionary, CC BY-SA 3.0