promethazine vs antiemetic

promethazine and antiemetic both are nouns.

Word	Noun	Adjective	Verb	Adverb
promethazine	Yes	No	No	No
antiemetic	Yes	No	No	No

As nouns, antiemetic is a hypernym of promethazine; that is, antiemetic is a word with a broader meaning than promethazine:

promethazine: antihistamine (trade name Phenergan) used to treat allergies; also an antiemetic used to treat motion sickness
antiemetic: a drug that prevents or alleviates nausea and vomiting

Other hypernyms of promethazine include antiemetic drug, antihistamine.

promethazine (noun)	antiemetic (noun)
antihistamine (trade name Phenergan) used to treat allergies; also an antiemetic used to treat motion sickness	a drug that prevents or alleviates nausea and vomiting