Source : Webster's Revised Unabridged Dictionary (1913)

Important \Im*por"tant\, a. [F. important. See {Import}, v. t.]
   1. Full of, or burdened by, import; charged with great
      interests; restless; anxious. [Obs.]

            Thou hast strength as much As serves to execute a
            mind very important.                  --Chapman.

   2. Carrying or possessing weight or consequence; of valuable
      content or bearing; significant; weighty.

            Things small as nothing . . . He makes important.
                                                  --Shak.

   3. Bearing on; forcible; driving. [Obs.]

            He fiercely at him flew, And with important outrage
            him assailed.                         --Spenser.

   4. Importunate; pressing; urgent. [Obs.] --Shak.

   Syn: Weighty; momentous; significant; essential; necessary;
        considerable; influential; serious.

Source : WordNet®

important
     adj 1: of great significance or value; "important people"; "the
            important questions of the day" [syn: {of import}]
            [ant: {unimportant}]
     2: 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: {significant}] [ant: {insignificant}]
     3: of extreme importance; vital to the resolution of a crisis;
        "a crucial moment in his career"; "a crucial election"; "a
        crucial issue for women" [syn: {crucial}] [ant: {noncrucial}]
     4: having authority or ascendancy or influence; "an important
        official"; "the captain's authoritative manner" [syn: {authoritative}]
     5: having or suggesting a consciousness of high position;
        "recited the decree with an important air"; "took long
        important strides in the direction of his office"