belch vs unconditioned reflex

belch and unconditioned reflex both are nouns.

Word	Noun	Adjective	Verb	Adverb
belch	Yes	No	Yes	No
unconditioned reflex	Yes	No	No	No

As nouns, unconditioned reflex is a hypernym of belch; that is, unconditioned reflex is a word with a broader meaning than belch:

belch: a reflex that expels gas noisily from the stomach through the mouth
unconditioned reflex: an automatic instinctive unlearned reaction to a stimulus

belch (noun)	unconditioned reflex (noun)
a reflex that expels gas noisily from the stomach through the mouth	an automatic instinctive unlearned reaction to a stimulus

belch (verb)	unconditioned reflex (verb)
expel gas from the stomach
become active and spew forth lava and rocks