retardation vs delay

retardation and delay both are nouns.

Word	Noun	Adjective	Verb	Adverb
retardation	Yes	No	No	No
delay	Yes	No	Yes	No

As nouns, delay is a hypernym of retardation; that is, delay is a word with a broader meaning than retardation:

retardation: the act of slowing down or falling behind
delay: the act of delaying; inactivity resulting in something being put off until a later time

Other hypernyms of retardation include holdup.

As nouns, delay is a hypernym of retardation; that is, delay is a word with a broader meaning than retardation:

Other hypernyms of retardation include hold, postponement, time lag, wait.

retardation (noun)	delay (noun)
the act of slowing down or falling behind	the act of delaying; inactivity resulting in something being put off until a later time
a decrease in rate of change	time during which some action is awaited
lack of normal development of intellectual capacities
any agent that retards or delays or hinders
the extent to which something is delayed or held back

retardation (verb)	delay (verb)
	cause to be slowed down or delayed
	stop or halt
	slow the growth or development of
	act later than planned, scheduled, or required