Delayed stress syndrome, also known as post-traumatic stress disorder (PTSD), is a mental health condition that affects people who have experienced or witnessed a traumatic event. There are a few synonyms for this condition, including combat stress reaction (CSR), shell shock, and battle fatigue. CSR is commonly used to describe PTSD in military members who have experienced combat situations. Shell shock was originally used to describe PTSD symptoms experienced by soldiers in World War I. Battle fatigue refers to the exhaustion and mental strain experienced by soldiers in war zones, which can lead to PTSD. Regardless of the term used, it is important for individuals experiencing PTSD to seek professional help and support.