keep up vs retain

keep up and retain both are verbs.

Word	Noun	Adjective	Verb	Adverb
keep up	No	No	Yes	No
retain	No	No	Yes	No

As verbs, retain is a hyponym of keep up; that is, retain is a word with a more specific, narrower meaning than keep up:

keep up: lengthen or extend in duration or space
retain: allow to remain in a place or position or maintain a property or feature

Other hyponyms of keep up include continue, keep, keep on.

keep up (verb)	retain (verb)
prevent from going to bed at night	keep in one's mind
keep informed	secure and keep for possible future use or application
maintain a required pace or level	allow to remain in a place or position or maintain a property or feature
keep in safety and protect from harm, decay, loss, or destruction	hold back within
lengthen or extend in duration or space