The story
From escape + -ment. The watch component is so called because it allows a tooth to escape from a pallet at each vibration.
Etymology from Wiktionary, CC BY-SA 4.0.
escapement
es·cape·mentToday it means: The linkage in a (watch) that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands. Full definition →