Source : Webster's Revised Unabridged Dictionary (1913)

Indefinite \In*def"i*nite\, a. [L. indefinitus. See {In-} not,
   and {Definite}.]
   1. Not definite; not limited, defined, or specified; not
      explicit; not determined or fixed upon; not precise;
      uncertain; vague; confused; obscure; as, an indefinite
      time, plan, etc.

            It were to be wished that . . . men would leave off
            that indefinite way of vouching, ``the chymists say
            this,'' or ``the chymists affirm that.'' --Boyle.

            The time of this last is left indefinite. --Dryden.

   2. Having no determined or certain limits; large and
      unmeasured, though not infinite; unlimited; as indefinite
      space; the indefinite extension of a straight line.

            Though it is not infinite, it may be indefinite;
            though it is not boundless in itself, it may be so
            to human comprehension.               --Spectator.

   3. Boundless; infinite. [R.]

            Indefinite and omnipresent God, Inhabiting eternity.
                                                  --W. Thompson
                                                  (1745).

   4. (Bot.) Too numerous or variable to make a particular
      enumeration important; -- said of the parts of a flower,
      and the like. Also, indeterminate.

   {Indefinite article} (Gram.), the word a or an, used with
      nouns to denote any one of a common or general class.

   {Indefinite inflorescence}. (Bot.) See {Indeterminate
      inflorescence}, under {Indeterminate}.

   {Indefinite proposition} (Logic), a statement whose subject
      is a common term, with nothing to indicate distribution or
      nondistribution; as, Man is mortal.

   {Indefinite term} (Logic), a negative term; as, the not-good.

   Syn: Inexplicit; vague; uncertain; unsettled; indeterminate;
        loose; equivocal; inexact; approximate.

Source : WordNet®

indefinite
     adj 1: vague or not clearly defined or stated; "must you be so
            indefinite?"; "amorphous blots of color having vague
            and indefinite edges"; "he would not answer so
            indefinite a proposal" [ant: {definite}]
     2: not decided or not known; "were indefinite about their
        plans"; "plans are indefinite"