adder vs viper

adder and viper both are nouns.

Word	Noun	Adjective	Verb	Adverb
adder	Yes	No	No	No
viper	Yes	No	No	No

As nouns, viper is a hypernym of adder; that is, viper is a word with a broader meaning than adder:

adder: small terrestrial viper common in northern Eurasia
viper: venomous Old World snakes characterized by hollow venom-conducting fangs in the upper jaw

adder (noun)	viper (noun)
small terrestrial viper common in northern Eurasia	venomous Old World snakes characterized by hollow venom-conducting fangs in the upper jaw
a machine that adds numbers
a person who adds numbers