To be in the limelight is to be the person everyone is looking at — newspapers, television, the crowd. We use it for fame, for a moment of public attention, and sometimes for the hard side of that: you cannot hide. Though actually, the first limelight was a real lamp. In old theatres they heated a piece of quicklime — a white powder made by burning limestone — until it glowed fiercely; that bright beam was the limelight, and the actor it fell on was the one to watch. So the lime here is not the green fruit. Today the lamp is gone, but the picture stayed. Spotlight is the closer modern word for the lamp; limelight is now mostly the attention. A little more at home in writing and set phrases than in short chat, but people still say it.