Chapter Bachelor's button to Backlog of B by Webster's Dictionary (1913 Edition)

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 friends. — 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 an offender. — To back water (Naut.), to reverse the action of the oars, paddles, or propeller, so as to force the boat or ship backward.

Back
(Back), v. i.

1. To move or go backward; as, the horse refuses to back.

2. (Naut.) To change from one quarter to another by a course opposite to that of the sun; — used of the wind.

3. (Sporting) To stand still behind another dog which has pointed; — said of a dog. [Eng.]

To back and fill, to manage the sails of a ship so that the wind strikes them alternately in front and behind, in order to keep the ship in the middle of a river or channel while the current or tide carries the vessel against the wind. Hence: (Fig.) To take opposite positions alternately; to assert and deny. [Colloq.] — To back out, To back down, to retreat or withdraw from a promise, engagement, or contest; to recede. [Colloq.]

Cleon at first . . . was willing to go; but, finding that he [Nicias] was in earnest, he tried to back out.
Jowett (Thucyd. )

Back
(Back), adv. [Shortened from aback.]

1. In, to, or toward, the rear; as, to stand back; to step back.

2. To the place from which one came; to the place or person from which something is taken or derived; as, to go back for something left behind; to go back to one's native place; to put a book back after reading it.

3. To a former state, condition, or station; as, to go back to private life; to go back to barbarism.

4. (Of time) In times past; ago. "Sixty or seventy years back." Gladstone.