Abstract Hip Hop description from Rate Your Music:
"A style of Hip Hop which eschews many of the genre's conventions, abstract hip-hop has become a fixture of the underground hip-hop scene in the 2000s. Lyrically, artists tend to focus on more abstract ideas such as existentialism or social institutions rather than everyday problems or braggadocio. The language and presentation of these lyrics also tends to avoid the more upfront, visceral language of typical Hip Hop, instead preferring extensive metaphors and symbolic word choice.
Musically, most abstract artists feature unconventional beats that musically are considered also Experimental Hip Hop, but Abstract Hip Hop is a genre classification based on lyrical content and not a musical style."
"Abstract music depends heavily on processed sounds where the concepts of rhythm and melody are dissolved and the sounds take on a complex inner structure that is constantly morphing and changing.
Abstract music usually focuses not on the known and familiar, but rather the alien and otherworldly, where the listener must find his own associations and meanings.
Abstract music can range from completely abstract soundscapes to songs that only implement abstract elements but within a more regular song structure with rhythms and melodies, with the latter type usually labeled abstract because of an unusual structure consisting of sound effects and unusual rhythms. A lot of times artists will aim for a psychedelic and dreamlike effect by implementing abstract elements."