Lead-off means happening first, or going before the others. A lead-off batter in baseball is the first to hit. A lead-off question is the first one asked. A lead-off song is the first on an album. It is most at home in American sports and meeting talk; in Britain people often just say opening or first. As a verb, to lead off means to start, but this word as you see it here is the describing word. This lead sounds like “leed.”