Why Does 'In A Rush' Mean To Hurry?

The word rush has its origin in Latin and is taken from the word recusare. Recusare means to give a cause again. The word 'again' suggests anxiousness to do again. It indicates a forward motion. Thus, when someone says "go ahead" or "do it again", it generally conveys a rush or a race or run. Thus, when someone is racing to do something, he is said to be in haste. That person does not do things at normal pace. He tries to precipitate all matters. Thus, rush illustrates a flow or passage that is noisy and fast.

Hurry is an act of haste. Something that is fast or in a state of hastened progress is hurry. Hence, the phrase 'in a rush' is equivalent to hurry.