adiabatic index vs ratio

adiabatic index and ratio both are nouns.

Word	Noun	Adjective	Verb	Adverb
adiabatic index	Yes	No	No	No
ratio	Yes	No	No	No

As nouns, ratio is a hypernym of adiabatic index; that is, ratio is a word with a broader meaning than adiabatic index:

adiabatic index: the ratio of the heat capacity at constant pressure (C_P) to heat capacity at constant volume (C_V).
ratio: the relative magnitudes of two quantities (usually expressed as a quotient)

adiabatic index (noun)	ratio (noun)
the ratio of the heat capacity at constant pressure (C_P) to heat capacity at constant volume (C_V).	the relation between things (or parts of things) with respect to their comparative quantity, magnitude, or degree
	the relative magnitudes of two quantities (usually expressed as a quotient)