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.
intron inÂ·tron (Ä­n'trÅn) n. A segment of a gene situated between exons that does not function in coding for protein synthesis. After transcription of a gene to messenger RNA, the transcriptions of introns are removed, and the exons are spliced together by enzymes before translation and assembly of amino acids into proteins. Compare exon.