Longman Dictionary of Contemporary English - bang

~1 n 1 a sudden loud noise caused by something such as a gun or an object hitting a hard surface  (The front door slammed with a loud bang.) 2 a hard knock or hit against something  (That was a nasty bang on the head.) 3 bangs AmE hair cut straight across your forehead; fringe1 (1) BrE 4 AmE informal a strong feeling of pleasure  (She got a real bang out of seeing the kids in the school play.) 5 go off with a bang to happen in a very successful way  (The party really went off with a bang!) ~2 v 1 »KNOCK/HIT STH« to hit something hard against something else, making a loud noise  (She banged the phone down.) + on  (They were banging on the door with their fists.) 2 »CLOSE STH« I always + adv/prep, to close something violently making a loud noise, or to make something close in this way  (She banged the door and stomped up the stairs. | bang shut)  (The window banged shut.) 3 »MAKE NOISE« to make a loud noise or noises + about/around/away  (I could hear the garage door banging in the wind.) 4 »HIT STH« to hit a part of your body or something you are carrying against something, especially by accident; bump1 (1)  (Bobby fell and banged his knee. | I slipped and banged the guitar against the door.) 5 be banging your head against a brick wall informal to be wasting your efforts by doing something that does not produce any results  (Trying to teach that class is like banging your head against a brick wall.) 6 »HAVE SEX« taboo to have sex with someone bang on phr v BrE informal to talk continuously about something in a boring way + about)  (I'm tired of politicians banging on about family values.) bang sth out phr v informal 1 to play a tune or song loudly and badly on a piano 2 to write something in a hurry, especially on a typewriter  (Danielle banged out a few letters, before going home for the day.) bang sb/sth up phr v BrE slang 1 to put someone in prison 2 AmE informal to seriously damage something  (a banged-up old Buick) ~3 adv 1 informal directly or exactly  (The train arrived bang on time.) 2 bang on spoken exactly correct  (Yes! Your answer's bang on!) 3 bang goes spoken used to show that you are unhappy because something you had hoped for will not happen  ($750 to repair the car? Bang goes my holiday.) 4 spoken in a sudden, violent way  (He slowed down, and bang! The car behind crashed straight into us!) ~4 interjection used to make a sound like a gun or bomb  ("Bang, bang - you're dead," Tommy shouted.)