The dismount verb is used in conjunction with mounts (ride-able animals such as horses). Both "dismount" and "dismount <mount>" are recognized by the game. You cannot dismount if your hands are full.
>dismount You climb down from the ebony leather saddle on a tall red roan draft horse and carefully detach some rough white leather reins from her bit.
>dismount You climb down from an athletic tan mustang and carefully detach some sleek brown reins from his bit.
At this time, horse saddles are not compatible with tortoise mounts.
>dismount tortoise You climb down from a smooth green giant tortoise's neck and carefully detach some green hemp leads from him.
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.