Synonyms for Defensive (same or very similar meaning)
WordNet sense 1 (an attitude of defensiveness (especially in the phrase `on the defensive')):
defensive attitudeWordNet sense 2 (attempting to justify or defend in speech or writing):
justificatory, justificativeWordNet sense 3 (offering or expressing apology):
apologetic, excusatoryFrom the ODE community, based on WordNetadd/edit