Meaning

1. to squeeze
2. to tighten, constrict or compress
3. to press (e.g., a button)
4. to pull (e.g., the trigger)
5. to grit (e.g., one's teeth), to clench (e.g., one's fist)
6. to push down (e.g., a toilet plunger)
7. to hold back
8. to hold on to something