old woman vs wormwood

old woman and wormwood both are nouns.

Word	Noun	Adjective	Verb	Adverb
old woman	Yes	No	No	No
wormwood	Yes	No	No	No

As nouns, wormwood is a hypernym of old woman; that is, wormwood is a word with a broader meaning than old woman:

old woman: herb with greyish leaves found along the east coast of North America; used as an ornamental plant
wormwood: any of several low composite herbs of the genera Artemisia or Seriphidium

old woman (noun)	wormwood (noun)
a woman who is old	any of several low composite herbs of the genera Artemisia or Seriphidium
herb with greyish leaves found along the east coast of North America; used as an ornamental plant