inexplicable
Impossible to explain or understand, even after trying hard.
Inexplicable means impossible to explain or understand. When something is inexplicable, you can't figure out why it happened or how it makes sense, no matter how hard you try.
If your normally friendly dog suddenly refuses to go near the backyard for no reason you can discover, that's inexplicable behavior. When a student who struggles with math suddenly aces the hardest test of the year without studying, their success might seem inexplicable to their teacher (until the teacher learns the student had been secretly getting extra help).
Some mysteries remain inexplicable for years before someone finally discovers the explanation. Scientists once found the northern lights inexplicable, until they learned about solar winds and Earth's magnetic field.
When something feels inexplicable, people often keep searching for answers. Sometimes they find them, sometimes they don't. True inexplicable events are rare: most puzzles have solutions if someone is patient and curious enough to find them.