What is "hook and eye"

Hook \Hook\ (h[oo^]k; 277), n. [OE. hok, AS. h[=o]c; cf. D. haak, G. hake, haken, OHG. h[=a]ko, h[=a]go, h[=a]ggo, Icel. haki, Sw. hake, Dan. hage. Cf. Arquebuse, Hagbut, Hake, Hatch a half door, Heckle.]

1. A piece of metal, or other hard material, formed or bent into a curve or at an angle, for catching, holding, or sustaining anything; as, a hook for catching fish; a hook for fastening a gate; a boat hook, etc.

2. That part of a hinge which is fixed to a post, and on which a door or gate hangs and turns.

3. An implement for cutting grass or grain; a sickle; an instrument for cutting or lopping; a billhook.

   Like slashing Bentley with his desperate hook.
   --Pope.

4. (Steam Engin.) See Eccentric, and V-hook.

5. A snare; a trap. [R.]
   --Shak.

6. A field sown two years in succession. [Prov. Eng.]

7. pl. The projecting points of the thigh bones of cattle; -- called also hook bones.

8. (Geog.) A spit or narrow cape of sand or gravel turned landward at the outer end; as, Sandy Hook in New Jersey.

9. (Sports) The curving motion of a ball, as in bowling or baseball, curving away from the hand which threw the ball; in golf, a curving motion in the direction of the golfer who struck the ball.

10. (Computers) A procedure within the encoding of a computer program which allows the user to modify the program so as to import data from or export data to other programs.

    By hook or by crook, one way or other; by any means, direct or indirect.
    --Milton. ``In hope her to attain by hook or crook.''
    --Spenser.

    Off the hook, freed from some obligation or difficulty; as, to get off the hook by getting someone else to do the job.

    Off the hooks, unhinged; disturbed; disordered. [Colloq.] ``In the evening, by water, to the Duke of Albemarle, whom I found mightly off the hooks that the ships are not gone out of the river.''
    --Pepys.

    On one's own hook, on one's own account or responsibility; by one's self. [Colloq. U.S.]
    --Bartlett.

    To go off the hooks, to die. [Colloq.]
    --Thackeray.

    Bid hook, a small boat hook.

    Chain hook. See under Chain.

    Deck hook, a horizontal knee or frame, in the bow of a ship, on which the forward part of the deck rests.

    Hook and eye, one of the small wire hooks and loops for fastening together the opposite edges of a garment, etc.

    Hook bill (Zo["o]l.), the strongly curved beak of a bird.

    Hook ladder, a ladder with hooks at the end by which it can be suspended, as from the top of a wall.

    Hook motion (Steam Engin.), a valve gear which is reversed by V hooks.

    Hook squid, any squid which has the arms furnished with hooks, instead of suckers, as in the genera Enoploteuthis and Onychteuthis.

    Hook wrench, a wrench or spanner, having a hook at the end, instead of a jaw, for turning a bolthead, nut, or coupling.

n. A matched hook and an eye (gloss: loop into which the hook can fit), used for fastening.

n. a kind of fastener used on clothing