In-universe, it would seem that, at least around the time of the Battle of Yavin, the Force was considered as somewhat of a folktale, a religion, or a bunch of parlour tricks.
Consider Admiral Motti's view, before he knew better:
Don't try to frighten us with your sorcerer's ways, Lord Vader. Your sad devotion to that ancient religion has not helped you conjure up the stolen data tapes, or given you clairvoyance enough to find the rebels' hidden fort... (choking noises)
And consider Han Solo's stance on it:
Hokey religions and ancient weapons are no match for a good blaster at your side, kid.
Kid, I've flown from one side of this galaxy to the other. I've seen a lot of strange stuff, but I've never seen anything to make me believe there's one all-powerful Force controlling everything. There's no mystical energy field that controls my destiny. It's all a lot of simple tricks and nonsense.