Behind one's back

Back Back (b[a^]k), n. [AS. b[ae]c, bac; akin to Icel., Sw., & LG. bak, Dan. bag; cf. OHG. bahho ham, Skr. bhaj to turn, OSlav. b[=e]g[u^] flight. Cf. {Bacon}.] 1. In human beings, the hinder part of the body, extending from the neck to the end of the spine; in other animals, that part of the body which corresponds most nearly to such part of a human being; as, the back of a horse, fish, or lobster. [1913 Webster]

2. An extended upper part, as of a mountain or ridge. [1913 Webster]

[The mountains] their broad bare backs upheave Into the clouds. --Milton. [1913 Webster]

3. The outward or upper part of a thing, as opposed to the inner or lower part; as, the back of the hand, the back of the foot, the back of a hand rail. [1913 Webster]

Methought Love pitying me, when he saw this, Gave me your hands, the backs and palms to kiss. --Donne. [1913 Webster]

4. The part opposed to the front; the hinder or rear part of a thing; as, the back of a book; the back of an army; the back of a chimney. [1913 Webster]

5. The part opposite to, or most remote from, that which fronts the speaker or actor; or the part out of sight, or not generally seen; as, the back of an island, of a hill, or of a village. [1913 Webster]

6. The part of a cutting tool on the opposite side from its edge; as, the back of a knife, or of a saw. [1913 Webster]

7. A support or resource in reserve. [1913 Webster]

This project Should have a back or second, that might hold, If this should blast in proof. --Shak. [1913 Webster]

8. (Naut.) The keel and keelson of a ship. [1913 Webster]

9. (Mining) The upper part of a lode, or the roof of a horizontal underground passage. [1913 Webster]

10. A garment for the back; hence, clothing. [Obs.] [1913 Webster]

A bak to walken inne by daylight. --Chaucer. [1913 Webster]

{Behind one's back}, when one is absent; without one's knowledge; as, to ridicule a person behind his back.

{Full back}, {Half back}, {Quarter back} (Football), players stationed behind those in the front line.

{To be on one's back} or {To lie on one's back}, to be helpless.

{To put one's back up} or {to get one's back up}, to assume an attitude of obstinate resistance (from the action of a cat when attacked). [Colloq.]

{To see the back of}, to get rid of.

{To turn the back}, to go away; to flee.

{To turn the back on one}, to forsake or neglect him. [1913 Webster]