weed killer vs chemical

weed killer and chemical both are nouns.

Word	Noun	Adjective	Verb	Adverb
weed killer	Yes	No	No	No
chemical	Yes	Yes	No	No

As nouns, chemical is a hypernym of weed killer; that is, chemical is a word with a broader meaning than weed killer:

weed killer: a chemical agent that destroys plants or inhibits their growth
chemical: material produced by or used in a reaction involving changes in atoms or molecules

Other hypernyms of weed killer include chemical substance.

weed killer (noun)	chemical (noun)
a chemical agent that destroys plants or inhibits their growth	material produced by or used in a reaction involving changes in atoms or molecules

weed killer (adjective)	chemical (adjective)
	relating to or used in chemistry
	of or made from or using substances produced by or used in reactions involving atomic or molecular changes