e-mail vs computer science

e-mail and computer science both are nouns.

Word	Noun	Adjective	Verb	Adverb
e-mail	Yes	No	Yes	No
computer science	Yes	No	No	No

e-mail (noun)	computer science (noun)
(computer science) a system of world-wide electronic communication in which a computer user can compose a message at one terminal that can be regenerated at the recipient's terminal when the recipient logs in	the branch of engineering science that studies (with the aid of computers) computable processes and structures

e-mail (verb)	computer science (verb)
communicate electronically on the computer