1210, "bag, sack," from Anglo-Fr. pokete (13c.), dim. of O.N.Fr. poque "bag," from Frank. *pokka "bag," from Gmc. *puk- (see poke (n.)). Meaning "small bag worn on the person, especially one sewn into a garment" is from c.1430. Mining sense is attested from 1850; military sense of "area held by troops surrounded by the enemy" is from 1918. The verb, with implications of dishonesty, is from 1637. Pocket-book (1617) was originally "a book-like case for papers, etc.;" meaning "a woman's purse" is from 1816. Pocket-knife is first recorded 1727; pocket-money is attested from 1632.

–noun

1.	an instrument for cutting, consisting essentially of a thin, sharp-edged, metal blade fitted with a handle.

2.	a knifelike weapon; dagger or short sword.

3.	any blade for cutting, as in a tool or machine.

–verb (used with object)

4.	to apply a knife to; cut, stab, etc., with a knife.

5.	to attempt to defeat or undermine in a secret or underhanded way.

–verb (used without object)

6.	to move or cleave through something with or as if with a knife: The ship knifed through the heavy seas.

—Idiom

7.	under the knife, in surgery; undergoing a medical operation: The patient was under the knife for four hours.