assay vs double check

assay and double check both are nouns.

Word	Noun	Adjective	Verb	Adverb
assay	Yes	No	Yes	No
double check	Yes	No	No	No

As nouns, double check is a hyponym of assay; that is, double check is a word with a more specific, narrower meaning than assay:

Other hyponyms of assay include countercheck, Apgar score, paternity test, stress test.

assay (noun)	double check (noun)
a quantitative or qualitative test of a substance (especially an ore or a drug) to determine its components; frequently used to test for the presence or concentration of infectious agents or antibodies etc.	something that checks the correctness of a previous check
an appraisal of the state of affairs
a written report of the results of an analysis of the composition of some substance
a substance that is undergoing an analysis of its components

assay (verb)	double check (verb)
analyze (chemical substances)
make an effort or attempt