'Obstacle' is Latin for 'something standing against you' — from 'stare' (to stand) + 'ob-' (against).
A thing that blocks one's way or prevents or hinders progress; an impediment or barrier.
From Old French 'obstacle' (13th century), from Latin 'obstāculum,' meaning 'a hindrance, obstacle,' from 'obstāre' meaning 'to stand before, to block,' composed of 'ob-' (against, in the way of) and 'stāre' (to stand). The Latin verb 'stāre' descends from the PIE root *steh₂- (to stand), one of the most prolific roots in the Indo-European language family. The suffix '-culum' is a Latin instrumental diminutive, giving the sense of 'a little thing that stands
The 'obstacle course' as a military training concept dates back to ancient Rome, where legionaries trained by running through barricaded paths — a practice whose Latin name would have used the very word 'obstāculum' that gave us 'obstacle.'