purple heart vs phenobarbitone

purple heart and phenobarbitone both are nouns.

Word	Noun	Adjective	Verb	Adverb
purple heart	Yes	No	No	No
phenobarbitone	Yes	No	No	No

As nouns, purple heart and phenobarbitone are synonyms defined as:

purple heart and phenobarbitone: a long-acting barbiturate used as a sedative

Other synonyms of purple heart include Luminal, phenobarbital, sodium thiopental.

purple heart (noun)	phenobarbitone (noun)
a long-acting barbiturate used as a sedative	a long-acting barbiturate used as a sedative