When people sunbathe, they sit or lie in a place where the sun shines on them, so that their skin becomes browner. Franklin swam and sunbathed at the pool every morning. + sunbather sunbathers sun·bather A week ago Bournemouth beach was thronged with sunbathers soaking up the 80 degrees heat. + sunbathing sun·bath·ing Nearby there is a stretch of white sand beach perfect for sunbathing. to sit or lie outside in the sun, especially in order to become brown