Pin down and Single out

Pin down verb - Attach with or as if with a pin.

Single out and pin down are semantically related in choose topic. In some cases you can use "Single out" instead a verb "Pin down", when it comes to topics like pick out.

Single out verb - To decide to accept (someone or something) from a group of possibilities.

Pin down and single out are semantically related in choose topic. Sometimes you can use "Pin down" instead a verb "Single out", if it concerns topics such as pick out.