The doorpost of a victualer's shop or inn, on which were chalked the scores of customers; hence, a score; a debt.

Haste or speed, like that of a messenger or mail carrier.

To travel with post horses; figuratively, to travel in haste.

To rise and sink in the saddle, in accordance with the motion of the horse, esp. in trotting.

With post horses; hence, in haste; as, to travel post.

To rise from the saddle in rhythm with the horse's trot.

ride Western style and bob up and down in the saddle in in rhythm with a horse's trotting gait