Any action that does not create a loop is busywork. Busywork is generally not that much fun, and tends toward repetitive, low agency or permutative actions. Such activity typically could be automated or skipped entirely, does not cause meaningful change in the game world and only the player's tolerance for it governs whether they will become bored or not.
Grinding in a massive multiplayer game is an example of busywork, but so is talking through the motions of branched dialogue common in roleplaying games, harvesting in social games or vacuuming-style exploration common to many adventure games.
