The official GemStone IV encyclopedia.
The dismount verb is used in conjunction with mounts (ridable animals such as horses).
Dismount when riding: Sliding one of your feet forward and securing it in the saddle's stirrup, you twist your body in toward your golden stallion as you slide down its side and dismount, then detach some glossy ebon leather reins from your stallion's bridle. Dismount when not riding: You are not mounted.
Prior to the Rumor Woods event of 2019, dismount as a verb had no functionality. Its usage resulted in the following messaging:
But you aren't on a horse to dismount.