backbend vs acrobatic stunt

backbend and acrobatic stunt both are nouns.

Word	Noun	Adjective	Verb	Adverb
backbend	Yes	No	No	No
acrobatic stunt	Yes	No	No	No

As nouns, acrobatic stunt is a hypernym of backbend; that is, acrobatic stunt is a word with a broader meaning than backbend:

backbend: an acrobatic feat in which the trunk is bent backward from a standing position until the hands touch the floor
acrobatic stunt: a stunt performed by an acrobat

Other hypernyms of backbend include acrobatic feat.

backbend (noun)	acrobatic stunt (noun)
an acrobatic feat in which the trunk is bent backward from a standing position until the hands touch the floor	a stunt performed by an acrobat