- someone who talks too much
- who speak a lot, be loquacious, often noisily or boastfully
- someone who lacks discretion or awareness in vocal situations
- someone who shares secrets that are meant to be kept private
- (literally) a fish with a big mouth – for example, a largemouth bass has a big mouth
- Your big mouth always gets you in trouble at school, Steven!
- My brother has a big mouth. He told our parents I was pregnant at 15.
- Shhhh! I didn’t mean to share that secret. But, unfortunately, my big mouth always gets the best of me.
- Jenny’s big mouth got her in trouble at church again. Whispering during silent moments.
- Look at the big mouth on that bass, Jerry! You could fit a coke can in it.
- His friends are scared of inviting him to the parties as he turns into a big mouth after a few drinks.
Although, there is no official dated or recorded origin of this idiomatic expression. One could say this saying is the result of Americanism and American culture, which would date back to the late 1800s and early 1900s. A big mouth became known as someone who talks too much or openly shares secrets they aren’t supposed to. It can be loosely compared to tight-lipped as that’s someone who can keep a secret at all costs.