backup vs computer science

backup and computer science both are nouns.

Word	Noun	Adjective	Verb	Adverb
backup	Yes	No	No	No
computer science	Yes	No	No	No

backup (noun)	computer science (noun)
the act of providing approval and support	the branch of engineering science that studies (with the aid of computers) computable processes and structures
(computer science) a copy of a file or directory on a separate storage device
a musical part (vocal or instrumental) that supports or provides background for other musical parts
someone who takes the place of another (as when things get dangerous or difficult)
an accumulation caused by clogging or a stoppage