armpit

An armpit is the area under your arm, usually sweaty and a bit smelly.

When we talk about an armpit, it's not exactly a glamorous topic, but we use this word all the time to refer to our own body or someone else's. Imagine you're trying to get comfortable while you're sitting on a bus or train – if your arm is sticking out and touching another person, you might start to sweat under your arm, right? We often call that area your armpit. Sometimes we also use this word in a more informal way when talking about someone's odor or body parts in general: "Sorry, my armpits are being really stinky today!" It can be used as a noun or a bit of an adjective – it usually depends on how you're using the sentence.