old man vs Artemisia absinthium

old man and Artemisia absinthium both are nouns.

Word	Noun	Adjective	Verb	Adverb
old man	Yes	No	No	No
Artemisia absinthium	Yes	No	No	No

As nouns, old man and Artemisia absinthium are synonyms defined as:

old man and Artemisia absinthium: aromatic herb of temperate Eurasia and North Africa having a bitter taste used in making the liqueur absinthe

Other synonyms of old man include absinthe, common wormwood, lad's love.

old man (noun)	Artemisia absinthium (noun)
an informal term for your father	aromatic herb of temperate Eurasia and North Africa having a bitter taste used in making the liqueur absinthe
a man who is very old
a familiar term of address for a man
(slang) boss
aromatic herb of temperate Eurasia and North Africa having a bitter taste used in making the liqueur absinthe