Used to label an unusually large number of occurrances of a disease or condition in one place. An autism cluster would be an unusually large number of cases of autism in (perhaps) a single locality. Clusters constitute evidence in the search for causes of diseases and conditions.
Top definition. jawn. a word used by Philly cats to describe anything and everything. NY cats interject with the word joint but it doesn't convey the same feelings.
Citizens Bank Park could also be called a jawn. (Photo: Jessica Rossi/CC BY-SA 2.0) Taylor Jones, a Ph.D student at the University of Pennsylvania, was unfamiliar with the bizarre stew of linguistic quirks in Philadelphia when he first started school there a few years ago.