further vs spur

further is not a noun while spur is a noun.

Word	Noun	Adjective	Verb	Adverb
further	No	Yes	Yes	Yes
spur	Yes	No	Yes	No

As verbs, spur is a hyponym of further; that is, spur is a word with a more specific, narrower meaning than further:

Other hyponyms of further include connive at, wink at, cultivate, foster, further, help, carry, feed, conduce, contribute, lead.

further (noun)	spur (noun)
	a sharp prod fixed to a rider's heel and used to urge a horse onward
	a railway line connected to a trunk line
	a verbalization that encourages you to attempt something
	tubular extension at the base of the corolla in some flowers
	any sharply pointed projection

further (adjective)	spur (adjective)
more distant in especially degree

further (verb)	spur (verb)
contribute to the progress or growth of	goad with spurs
promote the growth of	equip with spurs
	strike with a spur
	give heart or courage to
	incite or stimulate

further (adverb)	spur (adverb)
to or at a greater distance in time or space (`farther' is used more frequently than `further' in this physical sense)
to or at a greater extent or degree or a more advanced stage (`further' is used more often than `farther' in this abstract sense)
in addition or furthermore