- To run out a line.
- To change course.
- (of the wind in the northern hemisphere) To change direction in the clockwise fashion.
(Def. 1) 15th century from Middle English, vieren, meaning to let out or slacken. (Def. 2) 16th century from Latin, vertere, and then Old French, virer, meaning to turn. (Def. 3) Probably earlier than the 17th century, also from Old French, virer.
Nowadays mostly heard in reference to veering off course.
Rogers, J.G. (1985). Origins of Sea Terms. Mystic Seaport.