offensive has 12 distinct synonyms spread across 4 of its 7 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its 2 recorded opposites are defensive, inoffensive.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
violating or tending to violate or offend against
“violative of the principles of liberty”
for the purpose of attack rather than defense
“offensive weapons”
causing anger or annoyance
“offensive remarks”
unpleasant or disgusting especially to the senses
“offensive odors”
Synonyms, antonyms and the broader and narrower relations for offensive come from Princeton University’s WordNet. Full sources and licences.