“The lead vocalist (or main vocalist, lead vocals or lead singer) in popular music is typically the member of a group or band whose voice is the most prominent in a performance where multiple voices may be heard.  The lead singer either leads the vocal ensemble or sets against the ensemble as the dominant sound.  In vocal group performances, notably in soul and gospel music, and early rock and roll, the lead singer takes the main vocal part, with a chorus provided by other band members as backing vocalists.”
Wikipedia