pin down

Verb

pin down (third-person singular simple present pins down, present participle pinning down, simple past and past participle pinned down)

1. (transitive) To attach or secure with pins.
   • Pin down the tablecloth, so it doesn't blow away in the breeze.
   • There are approximately 1,000 places on British Railways where wagon brakes must be pinned down before trains proceed over severe falling gradients; the trains have to be brought to a stand for the brakes to be pinned down, and subsequently have again to be stopped for the brakes to be released.1955 March, “Modernisation and Re-Equipment of British Railways”, in Railway Magazine, pages 154, 171
2. (idiomatic, transitive) To identify something (e.g. a decision or plan) clearly or specifically.
   • Something is wrong, but I can't pin it down.
3. (transitive) To hold the opponent back-first so both his or her shoulders touch the mat or ground.

   Synonyms:

   pin

4. (idiomatic, transitive) To corner somebody in order to get a firm answer.
   • Let's try to pin him down on a price.