shower bath vs washup

shower bath and washup both are nouns.

Word	Noun	Adjective	Verb	Adverb
shower bath	Yes	No	No	No
washup	Yes	No	No	No

As nouns, washup is a hypernym of shower bath; that is, washup is a word with a broader meaning than shower bath:

shower bath: washing yourself by standing upright under water sprayed from a nozzle
washup: the act of washing yourself (or another person)

Other hypernyms of shower bath include bathing.

shower bath (noun)	washup (noun)
washing yourself by standing upright under water sprayed from a nozzle	the act of washing yourself (or another person)
booth for washing yourself, usually in a bathroom	the act of washing dishes