A soldier who is not a member of an official military force and who may not use regular army tactics.
One who does not regularly attend a venue.
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
A person employed to fight in an armed conflict who is not a member of the state or military group for which they are fighting and whose primary motivation is private gain.
One hired to engage in a figurative battle, as a corporate takeover, a lawsuit, or a political campaign.
Motivated by private gain.