Wiktionary
n. In rock music, an electric guitar that plays soloistically, usually playing melodically as opposed to strumming chords; supported by the rhythm guitar.
Wikipedia
Lead guitar is a guitar part which plays melody lines, instrumental fill passages, guitar solos, and occasionally, some riffs within a song structure. The lead is the featured guitar, which usually plays single-note-based lines or double-stops. In rock, heavy metal, blues, jazz, punk, fusion, some pop, and other music styles, lead guitar lines are usually supported by a second guitarist who plays rhythm guitar, which consists of accompaniment chords and riffs.
Usage examples of "lead guitar".
The next one was an old Eagles song that gave Stuart a chance to sing and muddle up the lead guitar riffs.
Airplane with Grace Slick on vocals, Norman Mailer on lead guitar, and good old Norman Bates on drums.
When it seemed impossible that Cassidy could carry this on much longer, the musician added a third refrain, a lilting lead guitar riff which joined into the mesh of notes, joining a consensus of musical opinion.
He and Kevin found a new Stress drummer and they practiced constantly, with Bill on lead guitar and vocal and Kevin on bass.
The lead guitar and the singer were fighting over the drummer on stage.
Murphy's lead guitar, Kasim is our drummer, and the soul man Franklin is on bass.