chum vs sidekick

chum and sidekick both are nouns.

Word	Noun	Adjective	Verb	Adverb
chum	Yes	No	No	No
sidekick	Yes	No	No	No

As nouns, chum and sidekick are synonyms defined as:

chum and sidekick: a close friend who accompanies his buddies in their activities

Other synonyms of chum include brother, buddy, crony, pal.

chum (noun)	sidekick (noun)
a large Pacific salmon with small spots on its back; an important food fish	a close friend who accompanies his buddies in their activities
bait consisting of chopped fish and fish oils that are dumped overboard to attract fish
a close friend who accompanies his buddies in their activities