the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)
important in effect or meaning; "a significant change in tax laws"; "a significant change in the Constitution"; "a significant contribution"; "significant details"; "statistically significant"
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"