to sit on something, usually a chair, in a relaxed position
Example:
- He sat back in his chair and started to read.
Extra examples:
- Just sit back and enjoy the show.
- She sat back and stretched out her legs.
to relax, especially by not getting too involved in or anxious about something
Example:
- She's not the kind of person who can sit back and let others do all the work.
- How can you sit back and watch him suffer?