Source : Webster's Revised Unabridged Dictionary (1913)

Significant \Sig*nif"i*cant\, a. [L. significans, -antis, p. pr.
   of significare. See {Signify}.]
   1. Fitted or designed to signify or make known somethingl
      having a meaning; standing as a sign or token; expressive
      or suggestive; as, a significant word or sound; a
      significant look.

            It was well said of Plotinus, that the stars were
            significant, but not efficient.       --Sir W.
                                                  Raleigh.

   2. Deserving to be considered; important; momentous; as, a
      significant event.

   {Significant figures} (Arith.), the figures which remain to
      any number, or decimal fraction, after the ciphers at the
      right or left are canceled. Thus, the significant figures
      of 25,000, or of .0025, are 25.

Significant \Sig*nif"i*cant\, n.
   That which has significance; a sign; a token; a symbol.
   --Wordsworth.

         In dumb significants proclaim your thoughts. --Shak.

Source : WordNet®

significant
     adj 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" [syn: {important}] [ant: {insignificant}]
     2: fairly large; "won by a substantial margin" [syn: {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" [ant: {nonsignificant}]
     4: rich in significance or implication; "a meaning look";
        "pregnant with meaning" [syn: {meaning(a)}, {pregnant}]