adiabatic index vs heat capacity ratio

adiabatic index and heat capacity ratio both are nouns.

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

As nouns, adiabatic index and heat capacity ratio are synonyms defined as:

adiabatic index and heat capacity ratio: the ratio of the heat capacity at constant pressure (C_P) to heat capacity at constant volume (C_V).

adiabatic index (noun)	heat capacity ratio (noun)
the ratio of the heat capacity at constant pressure (C_P) to heat capacity at constant volume (C_V).	the ratio of the heat capacity at constant pressure (C_P) to heat capacity at constant volume (C_V).