inexplicable
adj.impossible to explain or understand. You use this when something happens and there is no clear reason why.
adj.unable to be explained, accounted for, or understood through logic or reason. Often used to describe sudden changes in behavior or mysterious events.
“The car suddenly stopped for an inexplicable reason.”
“The team suffered an inexplicable loss despite being the heavy favorites to win the championship.”
“The detective was haunted by the inexplicable disappearance of the witness, as there were no signs of a struggle and the security cameras showed nothing unusual.”
Often used predicatively after linking verbs like 'remain' or 'seem'.
“It’s a decision that will no doubt please enemies of LGBTQ+ culture, but otherwise seems inexplicable.”
“Edney says the sequestering issue was an “inexplicable” and “still unexplained” failure that occurred in one of Victoria’s most high-profile criminal trials.”
From Middle English inexplicable, from Middle French inexplicable, from Latin inexplicābilis, from in- (“not”) + explicābilis (“explicable”). By surface analysis, in- + explicable.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.