To sour; to embitter.
To neutralize alkalis.
To make something (more) acidic or sour; to convert into an acid.
To begrime; to cake with dirt.
Dirt, grease, soot, etc. that is ingrained and difficult to remove.
A genre of urban music that emerged in London, England, in the early 2000s, primarily a development of UK garage, dancehall, and hip hop.