Chaser

wiktionary

ref

From Middle English chaser, chacer, chasour, borrowed from Old French chaceür, chaceor, from chacier(“to chase, hunt”); later senses from or influenced by chase(“pursue”) +‎ -er. Doublet of chasseur.

From chase(“groove; decorate metal”) +‎ -er.

etymonline

ref

chaser (n.)

c. 1300, "horse trained for chasing," agent noun from chase (v.), probably in some cases from Old French chaceor "huntsman, hunter." Meaning "water or mild beverage taken after a strong drink" is by 1894, U.S. colloquial. French had chasse (from chasser "to chase") "a drink of liquor taken (or said to be taken) to kill the aftertaste of coffee or tobacco," which was used in English from c. 1800.