The term 'TEE Precursor' can be solved by the three letter answer 'ESS'. This acronym stands for 'Exercise Stress Test', which is a type of medical test used to assess how well the heart and lungs are functioning during physical activity. The test involves monitoring the patient's heart rate, breathing rate, and blood pressure while they exercise on a treadmill or stationary bike. The results of the test can help doctors diagnose and treat various cardiovascular conditions.