WordWeb Online

1. Important in effect or meaning
   "a significant change in tax laws"; "a significant change in the Constitution"; "a significant contribution"; "significant details"; "statistically significant"
   - important
    
2. Fairly large
   - substantial
    
3. Too closely correlated to be attributed to chance and therefore indicating a systematic relation
   "the interaction effect is significant at the .01 level"; "no significant difference was found"
    
4. Rich in significance or implication
   - meaning, pregnant

See also: considerable, earthshaking, earth-shattering, epochal, epoch-making, evidential, evidentiary, fundamental, important, large, meaningful, momentous, monumental, noteworthy, of import, operative, portentous, probative, probatory, prodigious, profound, remarkable, significance, significantly, signify, world-shaking, world-shattering

Antonym: insignificant, nonsignificant

Encyclopedia: Significant