An annoying person, a nuisance.
Any destructive insect that attacks crops or livestock; an agricultural pest.
An animal regarded as a nuisance, destructive, or a parasite, vermin.
An invasive weed.
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.