to strike (something or somebody) with a whip or similar object
to beat hard against (something)
Rain lashed the forecourt
(+ into) to drive or incite somebody into a (particular state)
She lashed the crowd into a frenzy
said of an animal: to flick (the tail) quickly or sharply
said of rain: to beat against something
said of an animal's tail: to flick
lasher noun
[Middle English lashen, perhaps of imitative origin]