Leadlights, leaded lights or leaded windows are decorative windows made of small sections of glass supported in lead cames. The technique of creating windows using glass and lead came to be known as came glasswork. The term 'leadlight' could be used to describe any window in which the glass is supported by lead, but traditionally, a distinction is made between stained glass windows and leadlights; the former is associated with the ornate coloured-glass windows of churches and similar buildings, while the latter is associated with the windows of vernacular architecture and defined by its simplicity.

Since the traditional technique of setting glass into lead cames is the same in both cases, the division between 'leadlights' and 'stained glass' became less distinct during the late 20th century. The terms are now often incorrectly used interchangeably for any window employing this technique, while the term 'stained glass' is often applied to any windows, sculptures or works of art using coloured glass.