defend vs ward off

defend and ward off both are verbs.

Word	Noun	Adjective	Verb	Adverb
defend	No	No	Yes	No
ward off	No	No	Yes	No

As verbs, ward off is a hyponym of defend; that is, ward off is a word with a more specific, narrower meaning than defend:

Other hyponyms of defend include bulwark, protect, arrest, check, contain, hold back, stop, turn back.

defend (verb)	ward off (verb)
argue or speak in defense of	avert, turn away, or repel
state or assert	prevent the occurrence of; prevent from happening; to protect from or to keep away anything undesirable; to ward off
be on the defensive; act against an attack
protect against a challenge or attack
protect or fight for as a champion
fight against or resist strongly
be the defense counsel for someone in a trial