What is the Sanskrit word for 'courier'?

Dhoot

a courier in sanskrit is called Dhoot

for example check references for meghdhoot mens the messenger in the form of clouds.

actually not the courier but the carrier of the message is called a dhootaha.

There is special importnce for this Dhoota as he helped to communicate messages classified from normal to top secret .

He used to walk a long distances on foot to convey a mesages. He dont even bother to step onto the grounds of the enemies to convey a message of compromise from his king. There was an agreement among the kings that they would not kill a Dhoota even if is an alien enemy.