Pre-stressed is a building word, used most often with concrete. Pre-stressed concrete has strong wires or steel bars pulled tight inside it while it is made. When the concrete hardens, those wires stay tight and squeeze it, so it can carry more weight and crack less. Bridges, parking buildings, and long floors often use it. The stress here is the push and pull inside the material, not the worried feeling in your chest — though actually English uses the same word for both, which is why learners trip. You almost always meet this word as pre-stressed concrete, not about people.