The Collaborative International Dictionary of English v.0.48:
Back \Back\ (b[a^]k), v. t. [imp. & p. p. Backed (b[a^]kt); p.
pr. & vb. n. Backing.]
1. To get upon the back of; to mount.
I will back him [a horse] straight. --Shak.
2. To place or seat upon the back. [R.]
Great Jupiter, upon his eagle backed,
Appeared to me. --Shak.
3. To drive or force backward; to cause to retreat or recede;
as, to back oxen.
4. To make a back for; to furnish with a back; as, to back
5. To adjoin behind; to be at the back of.
A garden . . . with a vineyard backed. --Shak.
The chalk cliffs which back the beach. --Huxley.
6. To write upon the back of; as, to back a letter; to
indorse; as, to back a note or legal document.
7. To support; to maintain; to second or strengthen by aid or
influence; as, to back a friend. "The Parliament would be
backed by the people." --Macaulay.
Have still found it necessary to back and fortify
their laws with rewards and punishments. --South.
The mate backed the captain manfully. --Blackw. Mag.
8. To bet on the success of; -- as, to back a race horse.
To back an anchor (Naut.), to lay down a small anchor ahead
of a large one, the cable of the small one being fastened
to the crown of the large one.
To back the field, in horse racing, to bet against a
particular horse or horses, that some one of all the other
horses, collectively designated "the field", will win.
To back the oars, to row backward with the oars.
To back a rope, to put on a preventer.
To back the sails, to arrange them so as to cause the ship
to move astern.
To back up, to support; to sustain; as, to back up one's
To back a warrant (Law), is for a justice of the peace, in
the county where the warrant is to be executed, to sign or
indorse a warrant, issued in another county, to apprehend
To back water (Naut.), to reverse the action of the oars,
paddles, or propeller, so as to force the boat or ship