A term applied to differences, correlations, cause-and-effect relationships, etc., to indicate that they are probably not due to chance alone. Significant ordinarily indicates a probability of not less than 95 percent, while highly significant indicates a probability of not less than 99 percent.
SIGNIFICANT (STATISTICAL)
Meaning of SIGNIFICANT (STATISTICAL) in English
Environmental engineering English vocabulary. Английский словарь экологического инжиниринга. 2012