What is "bat bolt"

Bat \Bat\ (b[a^]t), n. [OE. batte, botte, AS. batt; perhaps fr. the Celtic; cf. Ir. bat, bata, stick, staff; but cf. also F. batte a beater (thing), wooden sword, battre to beat.]

1. A large stick; a club; specifically, a piece of wood with one end thicker or broader than the other, used in playing baseball, cricket, etc.

2. In badminton, tennis, and similar games, a racket.

3. A sheet of cotton used for filling quilts or comfortables; batting.

4. A part of a brick with one whole end; a brickbat.

5. (Mining) Shale or bituminous shale.
   --Kirwan.

6. A stroke; a sharp blow. [Colloq. or Slang]

7. A stroke of work. [Scot. & Prov. Eng.]

8. Rate of motion; speed. [Colloq.] ``A vast host of fowl . . . making at full bat for the North Sea.''
   --Pall Mall Mag.

9. A spree; a jollification. [Slang, U. S.]

10. Manner; rate; condition; state of health. [Scot. & Prov. Eng.]

    Bat bolt (Machinery), a bolt barbed or jagged at its butt or tang to make it hold the more firmly.
    --Knight.