1.Definition: important in effect or meaning
"A significant change in tax laws", "A significant change in the Constitution", "A significant contribution", "Significant details", "Statistically significant"
2.Definition: of considerable importance, size, or worth
3.Definition: rich in significance or implication
"A significant silence"
4.Definition: 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"