Source : Webster's Revised Unabridged Dictionary (1913)

Normal \Nor"mal\, a. [L. normalis, fr. norma rule, pattern,
   carpenter's square; prob. akin to noscere to know; cf. Gr. ?
   well known, ? gnomon, also, carpenter's square: cf. F.
   normal. See {Known}, and cf. {Abnormal}, {Enormous}.]
   1. According to an established norm, rule, or principle;
      conformed to a type, standard, or regular form; performing
      the proper functions; not abnormal; regular; natural;
      analogical.

            Deviations from the normal type.      --Hallam.

   2. (Geom.) According to a square or rule; perpendicular;
      forming a right angle. Specifically: Of or pertaining to a
      normal.

   3. (Chem.) Standard; original; exact; typical. Specifically:
      (a) (Quantitative Analysis) Denoting a solution of such
          strength that every cubic centimeter contains the same
          number of milligrams of the element in question as the
          number of its molecular weight.
      (b) (Chem.) Denoting certain hypothetical compounds, as
          acids from which the real acids are obtained by
          dehydration; thus, normal sulphuric acid and normal
          nitric acid are respectively {S(OH)6}, and {N(OH)5}.
      (c) (Organ. Chem.) Denoting that series of hydrocarbons in
          which no carbon atom is united with more than two
          other carbon atoms; as, normal pentane, hexane, etc.
          Cf. {Iso-}.

   {Normal equations} (Method of Least Squares), a set of
      equations of the first degree equal in number to the
      number of unknown quantities, and derived from the
      observations by a specified process. The solution of the
      normal equations gives the most probable values of the
      unknown quantities.

   {Normal group} (Geol.), a group of rocks taken as a standard.
      --Lyell.

   {Normal place} (of a planet or comet) (Astron.), the apparent
      place in the heavens of a planet or comet at a specified
      time, the place having been determined by a considerable
      number of observations, extending perhaps over many days,
      and so combined that the accidental errors of observation
      have largely balanced each other.

   {Normal school}, a school whose methods of instruction are to
      serve as a model for imitation; an institution for the
      training of teachers.

Normal \Nor"mal\, n. [Cf. F. normale, ligne normale. See
   {Normal}, a.]
   1. (Geom.) Any perpendicular.

   2. (Geom.) A straight line or plane drawn from any point of a
      curve or surface so as to be perpendicular to the curve or
      surface at that point.

   Note: The term normal is also used to denote the distance
         along the normal line from the curve to the axis of
         abscissas or to the center of curvature.

Source : WordNet®

normal
     adj 1: conforming with or constituting a norm or standard or level
            or type or social norm; not abnormal; "serve wine at
            normal room temperature"; "normal diplomatic
            relations"; "normal working hours"; "normal word
            order"; "normal curiosity"; "the normal course of
            events" [ant: {abnormal}]
     2: in accordance with scientific laws [ant: {paranormal}]
     3: being approximately average or within certain limits in e.g.
        intelligence and development; "a perfectly normal child";
        "of normal intelligence"; "the most normal person I've
        ever met" [ant: {abnormal}]
     4: forming a right angle

normal
     n : something regarded as a normative example; "the convention
         of not naming the main character"; "violence is the rule
         not the exception"; "his formula for impressing visitors"
         [syn: {convention}, {pattern}, {rule}, {formula}]