A nonconformist; an unusual or unconventional person, who may be rejected or disdained by others for this reason.
Used other than figuratively or idiomatically: see black, sheep.
A person who is not wholesome, honest, or trustworthy.
A worker who refuses to strike; a scab.
One who does not regularly attend a venue.
A soldier who is not a member of an official military force and who may not use regular army tactics.
without symmetry, regularity, or uniformity
rough
not regular; having sides that are not equal or angles that are not equal
whose faces are not all regular polygons (or are not equally inclined to each other)
nonstandard; not conforming to rules or expectations
not following the regular or expected patterns of inflection in a given language