play at something—
1. (of children) engage in a specified game:
- Nana had turned on the water for Michael’s bath. The two older children were playing at being mother and father.
2. perform smth. in a not very serious manner:
- It’s no good playing at business, you have to take it seriously.
3. fill a particular position in a sports team:
- Vasquez played at center forward and center midfield … and he led the team in goals scored.
play on something—
1. perform on a musical instrument:
- I’m no longer aware that I’m playing on a violin; I’m just expressing myself.
2. make use or advantage of smb.’s feelings:
- By playing on the old lady’s fears, the criminals were able to persuade her to give them her money.
3. emit light, a jet of water from a hose, etc. onto a surface:
- Searchlights played on the river upstream to light up any floating mines.
4. make clever use of some aspect of a particular word or idea, often for a humorous effect:
- Arbuthnot’s satire plays on the idea of society as a human body.