sit vs horseback riding

sit is not a noun while horseback riding is a noun.

Word	Noun	Adjective	Verb	Adverb
sit	No	No	Yes	No
horseback riding	Yes	No	No	No

sit (noun)	horseback riding (noun)
	travel by being carried on horseback
	the sport of sitting on the back of a horse while controlling its movements

sit (verb)	horseback riding (verb)
serve in a specific professional capacity
be in a position in which one's upper body is largely upright and supported by one's backside
show to a seat; assign a seat for
take a seat
be in session
sit and travel on the back of animal, usually while controlling its motions
assume a posture as for artistic purposes
work or act as a baby-sitter
be around, often idly or without specific purpose
be located or situated somewhere