Main, n.
 1. Strength; force; might; violent effort. [Obs., except in certain phrases.]
    There were in this battle of most might and main.   --R. of Gl.
 He 'gan advance,
 With huge force, and with importable main.   --Spenser.
 2. The chief or principal part; the main or most important thing. [Obs., except in special uses.]
    Resolved to rest upon the title of Lancaster as the main, and to use the other two . . . but as supporters.   --Bacon.
 3. Specifically: (a) The great sea, as distinguished from an arm, bay, etc. ; the high sea; the ocean. “Struggling in the main.” --Dryden. (b) The continent, as distinguished from an island; the mainland. “Invaded the main of Spain.” --Bacon. (c) principal duct or pipe, as distinguished from lesser ones; esp. Engin., a principal pipe leading to or from a reservoir; as, a fire main.
 Forcing main, the delivery pipe of a pump.
 For the main, or In the main, for the most part; in the greatest part.
 With might and main, or With all one's might and main, with all one's strength; with violent effort.
    With might and main they chased the murderous fox.   --Dryden.