simmering vs cookery

simmering and cookery both are nouns.

Word	Noun	Adjective	Verb	Adverb
simmering	Yes	No	No	No
cookery	Yes	No	No	No

As nouns, cookery is a hypernym of simmering; that is, cookery is a word with a broader meaning than simmering:

simmering: cooking in a liquid that has been brought to a boil
cookery: the act of preparing something (as food) by the application of heat

Other hypernyms of simmering include cooking, preparation.

simmering (noun)	cookery (noun)
cooking in a liquid that has been brought to a boil	the act of preparing something (as food) by the application of heat