Abacab, released in 1981, is the 11th studio album by British band Genesis. It reached No.1 in the UK, where it remained in the charts for 27 weeks.

The group initially wrote an album's worth of material which they subsequently discarded because they saw themselves as becoming, in Mike Rutherford's words, "a caricature of ourselves." In what he saw as a major turning point for the group, they made a decision to throw out any songs which sounded like anything they had done before.

The album continues the band's sharp stylistic shift, begun on the preceding album Duke, toward a radio-friendly pop music sound. "No Reply At All" features the Earth, Wind & Fire horn section (as did Collins' solo album Face Value earlier in 1981).

Genesis produced Abacab solely by themselves. Engineer Hugh Padgham, who assisted Collins on Face Value, would continue to work on Genesis and Collins recordings through the end of the decade.

The album takes its name from an early arrangement of the title track. Rutherford said on the US radio show In the Studio with Redbeard (which spotlighted Duke and Abacab in one episode): "There were three bits of music in 'Abacab', and we referred to them as 'section a', 'section b', and 'section c'... and at different times, they were in different order. We'd start with 'section a' and then have 'section c'... and at one point in time, it spelled Abacab. On the final version, it's not that at all, it's like 'Accaabbaac'."