Other forms: bangs, banging, banged
A bang is a sudden loud noise, one hard sound and then nothing. A door slamming in a draught, a balloon going up, the flat crack of a firework two streets away.
Bang is a verb as well: you bang the door, bang your knee on the table leg, bang on the wall when the neighbours are too loud. British English also uses it as an adverb meaning exactly — bang in the middle, bang on time, bang goes my weekend. In American English, bangs are a fringe, hair cut straight across the forehead. Go with a bang means to end brilliantly, and bang for your buck is what you get for the money you spend. A bang on the head is a knock, not an explosion.
1nounbangA sudden loud noise, like something exploding or hitting hard.
“The door shut with a bang that made everyone look up.”
2verbhitTo hit something hard and noisily, or to make a loud noise.
“He kept banging on the pipe until the water started moving.”
3nounsharpA sharp knock or blow.
“She took a bang on the elbow getting out of the car.”
4adverbexactlyExactly or precisely, in informal British English.
“The train pulled in bang on time.”
5nounhairHair cut straight across the forehead, in American English; used in the plural.
“She cut her own bangs with kitchen scissors.”
Too few real examples of this word to estimate which sense is commonest.
bang is a loud noise.
Before it was a noise it was a blow. Old Norse banga meant to pound or hammer, from Proto-Germanic *bangōną, to beat, and behind that Proto-Indo-European *bʰen-, to beat, hit, injure. English kept the hammering in the verb and let the sound of the hammering become the noun.
Proto-Indo-European
*bʰen- — to beat, hit, injure
Proto-Germanic
*bangōną — to beat, pound
Old Norse
banga — to pound, hammer
Old English
*bangian
Middle English
*bangen
English, today
bang
From Middle English bangen, from Old English bangian or borrowed from Old Norse banga (“to pound, hammer”); both from Proto-Germanic bangōną (“to beat, pound”), from Proto-Indo-European bʰen- (“to beat, hit, injure”). Cognate with Scots bang, bung (“to strike, bang, hurl, thrash, offend”), Icelandic banga (“to pound, hammer”), gmq-osw bånga "to hammer"; whence modern Swedish banka (“to knock, pound, bang”), Danish banke (“to beat”), bengel (“club”), Low German bangen, bangeln (“to strike, beat”), West Frisian bingel, bongel, Dutch bengel (“bell; rascal”), German Bengel (“club”), bungen (“to throb, pulsate”). In the sense of a fringe of hair, from bang off. In the sense of abrupt left turn, from Boston left and associated risk of a crash.
Etymology from Wiktionary, CC BY-SA