Meaning

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

adjective significant

adjective very intense

originInherited from Northern Middle English big, bigge (“powerful, strong”), possibly from a dialect of Old Norse. Ultimately perhaps a derivative of Proto-Germanic *bugja- (“swollen up, thick”), from Proto-Indo-European *bʰew-, *bu- (“to swell”), in which case big would be related to bogey, bugbear, and bug. Compare dialectal Norwegian bugge (“great man”), Low German Bögge, Boggelmann.

Etymology from Wiktionary, CC BY-SA 3.0