retained object vs object

retained object and object both are nouns.

Word	Noun	Adjective	Verb	Adverb
retained object	Yes	No	No	No
object	Yes	No	Yes	No

As nouns, object is a hypernym of retained object; that is, object is a word with a broader meaning than retained object:

retained object (noun)	object (noun)
an object in a passive construction	a tangible and visible entity; an entity that can cast a shadow
	the goal intended to be attained (and which is believed to be attainable)
	the focus of cognitions or feelings
	(computing) a discrete item that provides a description of virtually anything known to a computer
	(grammar) a constituent that is acted upon

retained object (verb)	object (verb)
	express or raise an objection or protest or criticism or express dissent
	be averse to or express disapproval of