noun

• (figurative, sometimes derogatory) An isolated, self-contained, segregated subsection, area or field of interest; often of minority or specialist interest.
  "Abraham Merritt wrote for the pulps and never in his lifetime achieved critical success. Yet he had a devoted following in the science fiction ghetto who admired the clarity of his style and his power to evoke moods."

adj

• (slang, informal) Unseemly and indecorous or of low quality; cheap; shabby, crude.
  "My apartment's so ghetto, the rats and cockroaches filed a complaint with the city!"
• (US, informal, often derogatory or offensive) Characteristic of the style, speech, or behavior of residents of a predominantly black or other ghetto in the United States.
  "The music I liked was very ghetto and gritty. It was the stuff that didn't really cross over much, but spoke to a roots black experience. People don't understand this now, but the falsetto, crying singers were the most ghetto back then."

verb

• (transitive) To confine (a specified group of people) to a ghetto.
  "This is, in brief, a part of the story of the ghettoing of a large segment of Denver's Negro population."