Srila Bhaktisiddhanta Sarasvati Thakura quotes the following definition of rasabhasa from the Bhakti-rasamrta-sindhu (Uttara-vibhaga, Ninth Wave, 1-3,20,22,24):

A mellow temporarily appearing transcendental but contradicting mellows previously stated and lacking some of a mellow's necessities is called rasabhasa, an overlapping mellow, by advanced devotees who know how to taste transcendental mellows. Such mellows are called uparasa (submellows), anurasa (imitation transcendental mellows) and aparasa (opposing transcendental mellows). Thus the overlapping of transcendental mellows is described as being first grade, second grade or third grade. When the twelve mellows-such as neutrality, servitorship and friendship-are characterized by adverse sthayi-bhava, vibhava and anubhava ecstasies, they are known as uparasa, submellows. When the seven indirect transcendental mellows and the dried up mellow of neutrality are produced by devotees and moods not directly related to Krsna and devotional service in ecstatic love, they are described as anurasa, imitation mellows. If Krsna and the enemies who harbor feelings of opposition toward Him are respectively the object and abodes of the mellow of laughter, the resulting feelings are called aparasa, opposing mellows. Experts in distinguishing one mellow from another sometimes accept some overlapping transcendental mellows (rasabhasa) as rasas due to their being pleasurable and tasteful. Srila Visvanatha Cakravarti Thakura says, paraspara-vairayor yadi yogas tada rasabhasah: "When two opposing transcendental mellows overlap, they produce rasabhasa, or an overlapping of transcendental mellows."