Main meaning : Short for mainline. To mainly play a specific character, or side, during a game. Of a road: to convert into a main or primary road. Of chief or leading importance; prime, principal. Chief, most important, or principal in extent, size, or strength; consisting of the largest part. (of force, strength, etc.) Full, sheer, undivided. Big; angry. Belonging to or connected with the principal mast in a vessel. Great in size or degree; important, powerful, strong, vast. Exceedingly, extremely, greatly, mightily, very, very much.