language vs diachronic

language is a noun but diachronic is not a noun.

Word	Noun	Adjective	Verb	Adverb
language	Yes	No	No	No
diachronic	No	Yes	No	No

language (noun)	diachronic (noun)
the mental faculty or power of vocal communication
the cognitive processes involved in producing and understanding linguistic communication
a systematic means of communicating by the use of sounds or conventional symbols
(language) communication by word of mouth
the text of a popular song or musical-comedy number
a system of words used to name things in a particular discipline

language (adjective)	diachronic (adjective)
	used of the study of a phenomenon (especially language) as it changes through time