Select the most appropriate meaning of the given idiom.

A kick in the teeth

A grave setback

The most appropriate meaning of the idiom "a kick in the teeth" is a grave setback. It is used to describe something that is very disappointing or frustrating, and that can be difficult to recover from. The idiom comes from the idea of being kicked in the teeth, which would be a very painful and unpleasant experience.

The other options are not correct.

• Severe toothache: This is not the same as a kick in the teeth.
• Removing tooth cavities: This is not the same as a kick in the teeth.
• Hitting someone hard: This can be part of a kick in the teeth, but it is not the whole meaning.