A highly pretentious and not very widely-used term applied to unconventional hip-hop music (most notably artists associated with anticon, but also such artists as Flying Lotus, Busdriver and Prefuse 73).
Synonyms include experimental hip-hop, avant-garde hip-hop and avant-hop.
Some conservative hip-hop fans claim that such music is not truly hip-hop.
A: "James has got such pretentious music taste!"
B: "I thought he liked rap?"
A: "Nah, he's a total hipster-hopper, he just listens to his lame-ass 'abstract hip-hop' bullshit!"