The word 'dismount' is both a noun (dismount, dismounts) and a verb (dismount, dismounts, dismounting, dismounted).
The verb 'dismount' is to get down from something (a horse, a bicycle); to remove from a support, setting, or mounting.
The noun 'dismount' is a word for a move in which a gymnast jumps off an apparatus or a rider gets off a horse or a bicycle.
The adjective form for the verb to dismount is dismounting.
The adjective form for the noun dismount is dismountable.