Vocabulary

Anyone know what an article of clothing called a “wife beater” is?

I was reading a vampire book and ran across this passage:

“As Butch stepped into the main room, he got a load of Rhage’s ensemble for the night: Black leather trench coat fell from his shoulders to his ankles. Black wife-beater was tucked into leathers. Shitkickers topped him out at six-eight or so.”

I was sure it was a kind of shoe, but that doesn’t fit here. So I checked my dictionary of costume and it wasn’t there at all. Then I ended up on Dictionary.com, and they didn’t have it. Wikipedia says it’s Australian for a sleeveless shirt, but that wouldn’t show under a coat, would it?

Ever heard of one before? What are they?