offensive vs loathsome

offensive is a noun but loathsome is not a noun.

Word	Noun	Adjective	Verb	Adverb
offensive	Yes	Yes	No	No
loathsome	No	Yes	No	No

As adjectives, offensive and loathsome are synonyms defined as:

Other synonyms of offensive include nauseating, nauseous, noisome, queasy, sickening, vile.

offensive (noun)	loathsome (noun)
the action of attacking an enemy

offensive (adjective)	loathsome (adjective)
unpleasant or disgusting especially to the senses	highly offensive; arousing aversion or disgust
causing anger or annoyance	causing or able to cause nausea
for the purpose of attack rather than defense
morally offensive
violating or tending to violate or offend against
causing or able to cause nausea