throw in vs interpose

throw in and interpose both are verbs.

Word	Noun	Adjective	Verb	Adverb
throw in	No	No	Yes	No
interpose	No	No	Yes	No

As verbs, throw in and interpose are synonyms defined as:

Other synonyms of throw in include come in, inject, interject, put in.

throw in (verb)	interpose (verb)
to insert between other elements	to insert between other elements
give up in the face of defeat of lacking hope; admit defeat	to put forth by way of intervention
add as an extra or as a gratuity	be or come between
	get involved, so as to alter or hinder an action, or through force or threat of force