Brewer's: Bolt

An arrow, a shaft (Anglo-Saxon, bolta; Danish, bolt; Greek, ballo, to cast; Latin, pello, to drive). A door bolt is a shaft of wood or iron, which may be shot or driven forward to secure a door. A thunderbolt is an hypothetical shaft cast from the clouds; an aerolite. Cupid's bolt is Cupid's arrow.

The fool's bolt is soon spent.

A foolish archer shoots all his arrows so heedlessly that he leaves himself no resources in case of need.

I must bolt.

Be off like an arrow. To bolt food. To swallow it quickly without waiting to chew it. To bolt out the truth. To blurt it out; also To bolt out, to exclude or shut out by bolting the door. To bolt. To sift, as flour is bolted. This has a different derivation to the above (Low Latin, bult-ella, a boulter, from an Old French word for coarse cloth).

I cannot bolt this matter to the bran, As Bradwarden and holy Austin can.

Dryden's version of the Cock and Fox.

Bolt from the Blue

(A). There fell a bolt from the blue. A sudden and wholly unexpected catastrophe or event occurred, like a “thunderbolt” from the blue sky, or flash of lightning without warning and wholly unexpected.

Namque Diespiter Igni corusco nubila dividens, Plerumque, per purum tonantes Egit equos volucremque currum. ...

Horace: 1 Ode xxxiv. 5, etc.

“On Monday, Dec. 22nd [1890], there fell a bolt from the blue. The morning papers announced that the men were out [on strike].”— Nineteenth Century, February, 1891, p. 246.

In this phrase the word “bolt” is used in the popular sense for lightning the Latin fulmen, the French foudre and tonnerre, in English sometimes for an aerolite. Of course, in strict scientific language, a flash of lightning is not a thunderbolt. Metaphorically, it means a sudden and wholly unexpected catastrophe, like a thunderbolt [flash of lightning] from a blue or serene sky.

German:

Wie ein Blitzstrahl aus blauem Aether. Italian: Comme un fulmine a ciel sereno. Latin: Audiit et coeli genitor de parte serena intonuit haevum. (Virgil: AEneid, ix. 630.)

Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894

Bolt in Tun

Bolognese School