Source:http://linkedlifedata.com/resource/umls/id/C0750502
NCI: A term applied to differences, correlations, cause-and-effect relationships, etc., to indicate that they are noticeable, probably too closely correlated to be attributed to chance and therefore indicating a systematic relation: substantial, fairly large; also having consequence or import, important in effect or meaning. In statistics significant ordinarily indicates a probability of not less than 95 percent, while highly significant indicates a probability of not less than 99 percent.