Loudmouth (noun)

A person who talks excessively or loudly, often in a boastful or attention-seeking manner.

Origin:

From the combination of the word loud and the word mouth, meaning someone who talks loudly or excessively.

Examples:

1. He's always been a loudmouth, never letting anyone else speak.
2. She can't stand loudmouths, they always try to show off.
3. The loudmouth in the back of the class was constantly interrupting the teacher.
4. He's always the loudmouth at parties, telling everyone how great he is.
5. She's a bit of a loudmouth, but she means well and is generally good-natured.