offend vs blunder

offend is not a noun while blunder is a noun.

Word	Noun	Adjective	Verb	Adverb
offend	No	No	Yes	No
blunder	Yes	No	Yes	No

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

offend (noun)	blunder (noun)
	an embarrassing mistake

offend (verb)	blunder (verb)
hurt the feelings of	utter impulsively
cause to feel resentment or indignation	make one's way clumsily or blindly
strike with disgust or revulsion	commit a faux pas or a fault or make a serious mistake
act in disregard of laws, rules, contracts, or promises