Clumsy or inept with both hands (i.e., the opposite of ambidextrous, which literally means both right-handed; note that ancient Rome enormously favoured right-handedness, as China has in modern times)

Skilled or able with both hands (used generally in protest against the term ambidextrous because it implies right-handedness is preferable or ideal - ergo, this term is most commonly used by left-handed people, and also by hipsters and English majors who want to show of their knowledge of etymology and generally feel superior; very few people who use the term [ambisinister] are technically ambidextrous)

See also [ambisinistrous], which has the same meanings and the same roots (however, the adjective [sinistrous] has been almost universally replaced by sinister over the last several centuries).