Defensiveness is a term that is used to mean many things. It can refer to someone who blames circumstances, luck, or others when things don't work out. Or someone who creates excuses for not having done something. Defensive people tend to argue back forcefully and get angry when criticized or feel cornered by someone. Defensiveness is not uncommon with people who have a fragile self-esteem but also emerges as part of a troublesome dynamic between people who don't know how to resolve conflict effectively.
Patricia and Ken have struggled with a troubled marriage for many years and entered therapy at the point at which they were contemplating divorce. Their arguments had escalated to the point of mutual slander and they could hardly be contained in the treatment room. Each complained that the other was provocative, argumentative, and "unable to communicate." 'Attack and defend' seemed to be their primary communication style.