lash 1 
(lăsh)
(lăsh)n.
1.
a. A stroke or blow with or as if with a whip.
b. A whip.
c. The flexible portion of a whip, such as a plait or thong.
2. Punishment administered with a whip.
3.
a. A lacerating presence or power: the lash of conscience.
b. A caustic verbal attack.
4. An eyelash.
v. lashed, lash·ing, lash·es
v.tr.
1. To strike with or as if with a whip.
2. To strike against with force or violence: sleet lashing the roof.
3. To beat or swing rapidly: The alligator lashed its tail in the water.
4. To make a scathing oral or written attack against.
5. To drive or goad; sting: words that lashed them into action.
v.intr.
1. To move swiftly or violently; thrash: heard the snake lashing about in the leaves.
2.
a. To aim a sudden blow; strike: The mule lashed out with its hind legs.
b. To beat; flail: waves lashing at the shore.
3. To make a scathing verbal or written attack. Often used with out: lashed out at her critics during the interview.
[Middle English, probably from lashen, to deal a blow, perhaps of imitative origin.]
lasher n.