Definitions:

1. To talk continuously, often in a way that may be perceived as annoying, trivial, or overly talkative. VERB
   • She could yap away for hours on end about her favorite TV shows.
2. Used to describe someone speaking at length without much substance or without allowing others to contribute to the conversation. VERB
   • As soon as she started talking, she would yap away until someone interrupted her.

Synonyms:

• jaw
• rattle on
• yack