Webster's Revised Unabridged Dictionary · 1913

Clack

Clack , intransitive verb

[Probably of imitative origin; compare French claquer to clap, crack, Dutch klakken, Middle High German klac crack, Ir. clagaim I make a noise, ring. Compare Clack, n., Clatter, Click.]

1.
To make a sudden, sharp noise, or a succession of such noises, as by striking an object, or by collision of parts; to rattle; to click.
We heard Mr.Hodson's whip clacking on the ahoulders of the poor little wretches. — Thackeray
2.
To utter words rapidly and continually, or with abruptness; to let the tongue run.

Clack , transitive verb

1.
To cause to make a sudden, sharp noise, or succession of noises; to click.
2.
To utter rapidly and inconsiderately. — Feltham
Collocations (1)
To clack wool , to cut off the sheep's mark, in order to make the wool weigh less and thus yield less duty [English]

Clack , noun

[Compare French claque a slap or smack, Middle High German klac crack, Welsh clec crack, gossip. See Clack, transitive verb]

1.
A sharp, abrupt noise, or succession of noises, made by striking an object.
2.
Anything that causes a clacking noise, as the clapper of a mill, or a clack valve.
3.
Continual or importunate talk; prattle; prating.
Whose chief intent is to vaunt his spiritual clack. — South
Collocations (4)
Clack box (Machinery) , the box or chamber in which a clack valve works.
Clack dish , a dish with a movable lid, formerly carried by beggars, who clacked the lid to attract notice. — Shakespeare
Clack door (Mining) , removable cover of the opening through which access is had to a pump valve.
Clack valve (Machinery) , a valve; esp. one hinged at one edge, which, when raised from its seat, falls with a clacking sound.