1570s, "having or conveying a meaning," from Latin significantem (nominative significans), present participle of significare "make known, indicate" (see signify). Earlier in the same sense was significative; also significate (adj.) "indicated, signified"(early 15c.).
From 1590s as "serving as a sign or indication." Often "having a special or secret meaning," hence "important, weighty" (1761). Related: Significantly. The scientific significant figure is from 1680s. Significant other is attested by 1961, in psychology, "the most influential other person in the patient's world."
updated on October 24, 2022