I think the TV show "COPS" had a lot do with the creation of this word. Every time they showed a guy getting arrested for beating his wife he was wearing one of those sleeveless undershirts.
Virgil's got his wifebeater on, looks like Helen's gonna get taught a lesson tonight!
By Loreen
Wifebeater
An A formed white, tight, T-Shirt normally produced for men but also worn by women, intended for wear under shirts. Its reputation comes from those wearing the shirts while engaged indomestic violence.
A white, tank top typically worn by white trash men who beat their wives. NO wifebeater is complete without a 10 pound overweight/underweight guy to wear it and mustard stains :)
Ross Creed - "Mary-Anne! Get me a beer!"
Mary-Anne - "We aint got no beer!"
Ross Creed - "Well then get me a hotdog bitch!"
Mary-Anne - "Here ya go.."
*Ross Hits wife pathetically while spilling mustard all over his wifebeater*
By Fay
Wifebeater
Usually refers to any style of (usually) tight-fitting cotton shirts primarily worn by men as undershirts. Any of the types of white t-shirt or tank top that you can usually find sold in packages by the men's underwear can be classfied as a wifebeater.
While the "wifebeater" is worn primarily by men -- and presumably got the name because it is most often depicted as being worn as outerwear by men who beat their wives -- lots of women have taken to wearing them too. This is particularly true in the case of the cotton ribbed tank top, which can now be found sold as outerwear for women as well as men, and which can also be found in several other colors besides white.
In Australian slang, "wifebeater" always referred to a dark bluesinglet, such as is typically worn by truckers. It's only recently that we in Australia have heard the word coming from other parts of the world, and elsewhere it refers to a white singlet.
White, ribbed, skin-tight tank top, most excellent for showing off a dude's pecs, shoulders, arms, underarms, armpit hair, and natural B.O. Leaves a sweet tan line when worn on a summer day.