1.NounIn fictional or historical writings about chivalric romances: a quest embarked upon by a knight or other person which is not the main quest.
2.NounA quest given to a player which has no direct bearing on the outcome of the main campaign or story of a video game, but often provides additional rewards.
"Completion of a sidequest often results in the acquisition of money or items that are otherwise unavailable, or unlocks another sidequest.; That celebrity keeps completing random sidequests like hosting award shows."
3.NounA real-world action or task which a person does in addition to or instead of a main action or task.
"That celebrity keeps completing random sidequests like hosting award shows."