Definition:

Mount can mean slightly different things in the horse world. When you ride a horse, you’re said to be mounted. Getting on a horse is mounting up. In these two examples, variations of the word mount are used as verbs.  The horse you ride is called your mount. In this case, the word mount is used as a noun, and another way to say riding horse.
Dismounting is the act of getting off of the horse's back after riding.

Falls are said to be unscheduled dismounts.
Pronunciation: m ow nt

Examples: Because his horse was very tall, he climbed on a large rock to mount.