"friend," 1680s, originally university slang for "roommate," from alternative spelling of cham, short for chamber(mate); typical of the late-17c. fondness for clipped words. Among derived forms used 19c. were chumship; chummery "shared bachelor quarters," chummage "system of quartering more than one to a room."
"fish bait," 1857, perhaps from Scottish chum "food."
: Augie, start dumping the chum oververb
To throw ground-up bait into the water to attract fish: to chum for blues
[1850s+; origin unknown]
(also chum around): He chums with Georgie Ogle (1880s+)
[origin uncertain, but earlier uses strongly suggest chamber-mate or chamber-fellow as the etymon]