quas-

(Latin: to make void, annul; originally from the Latin meaning of, "to shake violently, to shatter")


quash 1: To set aside or annul, especially by judicial action.
2. In law, to overthrow; to abate; to vacate; to annul; to make void; that is, "to quash an indictment".

quash 2: To crush or forcibly suppress; such as, "to quash the demonstration.".

squash
1. To squeeze, beat, or flatten to a pulp or a flattened mass; to crush.
2. To put down or to suppress.
squassation
A shaking, beating, pounding.