unprepared; off guard
Describes being without preparation or readiness, often in a situation where one is caught off guard.
The enemy was struck while off guard.
It is risky to go into the real thing unprepared.
careless; imprudent; indiscreet; inadvertent
Used for actions, remarks, or handling of things done without enough caution or forethought; common in 不用意な発言 and 不用意に.
His careless remark became a major problem.
Please do not enter personal information carelessly.
He made a careless remark at the meeting and surprised everyone.
You shouldn't carelessly open the door.
Careless actions can sometimes lead to accidents.
He took advantage of his opponent's unguarded moment to turn the game around.