The term LIFE LINE is composed of two crossword solutions, AORTA (5 letters) and EKG (3 letters). An AORTA is the main artery in the human body that carries oxygen-rich blood from the heart to the rest of the body. An electrocardiogram (EKG) is a test that measures the electrical activity of the heart, which can help diagnose heart conditions. Together, these two solutions represent the life line of the human body, as the AORTA carries oxygen-rich blood to the body and the EKG monitors the heart's electrical activity.