fall by the wayside vs throw in

fall by the wayside and throw in both are verbs.

Word	Noun	Adjective	Verb	Adverb
fall by the wayside	No	No	Yes	No
throw in	No	No	Yes	No

As verbs, fall by the wayside and throw in are synonyms defined as:

fall by the wayside and throw in: give up in the face of defeat of lacking hope; admit defeat

Other synonyms of fall by the wayside include chuck up the sponge, drop by the wayside, drop out, give up, quit, throw in the towel.

fall by the wayside (verb)	throw in (verb)
give up in the face of defeat of lacking hope; admit defeat	to insert between other elements
	give up in the face of defeat of lacking hope; admit defeat
	add as an extra or as a gratuity