yawn vs instinctive reflex

yawn and instinctive reflex both are nouns.

Word	Noun	Adjective	Verb	Adverb
yawn	Yes	No	Yes	No
instinctive reflex	Yes	No	No	No

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

yawn: an involuntary intake of breath through a wide open mouth; usually triggered by fatigue or boredom
instinctive reflex: an automatic instinctive unlearned reaction to a stimulus

yawn (noun)	instinctive reflex (noun)
an involuntary intake of breath through a wide open mouth; usually triggered by fatigue or boredom	an automatic instinctive unlearned reaction to a stimulus

yawn (verb)	instinctive reflex (verb)
utter a yawn, as from lack of oxygen or when one is tired
be wide open