The term PART OF PTSD can be summarized by the crossword solution of STRESS. Post-traumatic STRESS disorder (PTSD) is a mental health condition that is triggered by a terrifying event. It can cause a range of symptoms, including flashbacks, nightmares, and severe anxiety. STRESS is one of the most common symptoms of PTSD, and can be caused by a variety of factors, such as traumatic memories, fear of the future, and difficulty sleeping.