A puzzling circumstance.
A difficulty that has to be resolved or dealt with.
A set of moves required to complete a climb.
A question to be answered, schoolwork exercise.
Objection.
Difficulty in accepting or understanding or refusal to accept or understand.
Causing a problem; problematic; troublesome.
Difficult to train or guide; unruly.
The act of one who tarries; a waiting or staying behind.