lâcher

From Old French lascher (13th century) "to loosen, release from a vow", earlier laschier (1080, Chanson de Roland), which goes back to Vulgar Latin *lassicare, a dissimilated form of *laxicare, a frequentative of Latin laxare "to relax, loosen, slacken; to become relaxed", from which also come the French words laisser as well as the learned formations laxative, laxist and relax.