- To attach or secure with pins.
- Pin down the tablecloth, so it doesn't blow away in the breeze.
- (idiomatic) To identify something (e.g. a decision or plan) clearly or specifically.
- Something is wrong, but I can't pin it down.
- (wrestling) To hold the opponent back-first so both his or her shoulders touch the mat.
- (idiomatic) To corner somebody in order to get a firm answer.
- Let's try to pin him down on a price.