Source : Webster's Revised Unabridged Dictionary (1913)

Begin \Be*gin"\, v. i. [imp. & p. p. {Began}, {Begun}; p. pr. &
   vb. n. {Beginning}.] [AS. beginnan (akin to OS. biginnan, D.
   & G. beginnen, OHG. biginnan, Goth., du-ginnan, Sw. begynna,
   Dan. begynde); pref. be- + an assumed ginnan. [root]31. See
   {Gin} to begin.]
   1. To have or commence an independent or first existence; to
      take rise; to commence.

            Vast chain of being! which from God began. --Pope.

   2. To do the first act or the first part of an action; to
      enter upon or commence something new, as a new form or
      state of being, or course of action; to take the first
      step; to start. ``Tears began to flow.'' --Dryden.

            When I begin, I will also make an end. --1 Sam. iii.
                                                  12.

Begun \Be*gun"\,
   p. p. of {Begin}.

Source : WordNet®

begin
     v 1: take the first step or steps in carrying out an action; "We
          began working at dawn"; "Who will start?"; "Get working
          as soon as the sun rises!"; "The first tourists began to
          arrive in Cambodia"; "He began early in the day"; "Let's
          get down to work now" [syn: {get down}, {get}, {start
          out}, {start}, {set about}, {set out}, {commence}] [ant:
           {end}]
     2: have a beginning, in a temporal, spatial, or evaluative
        sense; "The DMZ begins right over the hill"; "The second
        movement begins after the Allegro"; "Prices for these
        homes start at $250,000" [syn: {start}] [ant: {end}]
     3: set in motion, cause to start; "The U.S. started a war in
        the Middle East"; "The Iraqis began hostilities"; "begin a
        new chapter in your life" [syn: {lead off}, {start}, {commence}]
        [ant: {end}]
     4: begin to speak or say; "Now listen, friends," he began
     5: be the first item or point, constitute the beginning or
        start, come first in a series; "The number 'one' begins
        the sequence"; "A terrible murder begins the novel"; "The
        convocation ceremoney officially begins the semester"
     6: have a beginning, of a temporal event; "WWII began in 1939
        when Hitler marched into Poland"; "The company's Asia tour
        begins next month"
     7: have a beginning characterized in some specified way; "The
        novel begins with a murder"; "My property begins with the
        three maple trees"; "Her day begins with a work-out"; "The
        semester begins with a convocation ceremony" [syn: {start}]
     8: begin an event that is implied and limited by the nature or
        inherent function of the direct object; "begin a cigar";
        "She started the soup while it was still hot"; "We started
        physics in 10th grade" [syn: {start}]
     9: achieve or accomplish in the least degree, usually used in
        the negative; "This economic measure doesn't even begin to
        deal with the problem of inflation"; "You cannot even
        begin to understand the problem we had to deal with during
        the war"
     10: begin to speak, understand, read, and write a language; "She
         began Russian at an early age"; "We started French in
         fourth grade"
     [also: {begun}, {beginning}, {began}]

begun
     See {begin}