Definitions
1.nounAn (often walled) area of a city in which Jews are concentrated by force and law. (Used particularly of areas in medieval Italy and in Nazi-controlled Europe.)
2.nounAn (often impoverished) area of a city inhabited predominantly by members of a specific nationality, ethnicity or race.
3.nounAn area in which people who are distinguished by sharing something other than ethnicity concentrate or are concentrated.
4.noun(sometimes derogatory) An isolated, self-contained, segregated subsection, area or field of interest; often of minority or specialist interest.