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.
An act of sitting down, especially with other people in some form of social exchange.
A sit-in, a protest of civil disobedience by people sitting and refusing to move.
Intended to be done, used, consumed etc. while sitting.