Melba toast vs toast

Melba toast and toast both are nouns.

Word	Noun	Adjective	Verb	Adverb
Melba toast	Yes	No	No	No
toast	Yes	No	Yes	No

As nouns, toast is a hypernym of Melba toast; that is, toast is a word with a broader meaning than Melba toast:

Melba toast (noun)	toast (noun)
very thin crisp brown toast	slices of bread that have been toasted
	a drink in honor of or to the health of a person or event
	a celebrity who receives much acclaim and attention
	a person in desperate straits; someone doomed

Melba toast (verb)	toast (verb)
	make brown and crisp by heating
	propose a toast to