elusive
Hard to find, catch, or fully understand.
Elusive means difficult to find, catch, or achieve. When something is elusive, it seems to slip away just when you think you've got it, like trying to catch a lizard that darts under a rock the moment you reach for it.
A student might chase an elusive answer on a difficult math problem, understanding parts of it but not quite seeing the full solution. A soccer player might pursue an elusive goal, coming close to scoring several times but never quite getting the ball in the net. Scientists often search for elusive cures to diseases, working for years to find answers that remain just out of reach.
The word carries a sense of frustration mixed with determination. Something elusive isn't impossible, it's just maddeningly hard to pin down. A shy classmate might seem elusive at recess, always disappearing before you can talk to them. Success can feel elusive when you're learning something challenging, like playing the violin or mastering division.
When you finally catch or achieve something elusive, the victory feels especially sweet precisely because it was so hard to reach.