Source : Webster's Revised Unabridged Dictionary (1913)

Sin \Sin\, n. [OE. sinne, AS. synn, syn; akin to D. zonde, OS.
   sundia, OHG. sunta, G. s["u]nde, Icel., Dan. & Sw. synd, L.
   sons, sontis, guilty, perhaps originally from the p. pr. of
   the verb signifying, to be, and meaning, the one who it is.
   Cf. {Authentic}, {Sooth}.]
   1. Transgression of the law of God; disobedience of the
      divine command; any violation of God's will, either in
      purpose or conduct; moral deficiency in the character;
      iniquity; as, sins of omission and sins of commission.

            Whosoever committeth sin is the servant of sin.
                                                  --John viii.
                                                  34.

            Sin is the transgression of the law.  --1 John iii.
                                                  4.

            I think 't no sin. To cozen him that would unjustly
            win.                                  --Shak.

            Enthralled By sin to foul, exorbitant desires.
                                                  --Milton.

   2. An offense, in general; a violation of propriety; a
      misdemeanor; as, a sin against good manners.

            I grant that poetry's a crying sin.   --Pope.

   3. A sin offering; a sacrifice for sin.

            He hath made him to be sin for us, who knew no sin.
                                                  --2 Cor. v.
                                                  21.

   4. An embodiment of sin; a very wicked person. [R.]

            Thy ambition, Thou scarlet sin, robbed this
            bewailing land Of noble Buckingham.   --Shak.

   Note: Sin is used in the formation of some compound words of
         obvious signification; as, sin-born; sin-bred,
         sin-oppressed, sin-polluted, and the like.

   {Actual sin},

   {Canonical sins},

   {Original sin},

   {Venial sin}. See under {Actual}, {Canonical}, etc.

   {Deadly}, or

   {Mortal},

   {sins} (R. C. Ch.), willful and deliberate transgressions,
      which take away divine grace; -- in distinction from
      vental sins. The seven deadly sins are pride,
      covetousness, lust, wrath, gluttony, envy, and sloth.

   {Sin eater}, a man who (according to a former practice in
      England) for a small gratuity ate a piece of bread laid on
      the chest of a dead person, whereby he was supposed to
      have taken the sins of the dead person upon himself.

   {Sin offering}, a sacrifice for sin; something offered as an
      expiation for sin.

   Syn: Iniquity; wickedness; wrong. See {Crime}.

Actual \Ac"tu*al\ (#; 135), a. [OE. actuel, F. actuel, L.
   actualis, fr. agere to do, act.]
   1. Involving or comprising action; active. [Obs.]

            Her walking and other actual performances. --Shak.

            Let your holy and pious intention be actual; that is
            . . . by a special prayer or action, . . . given to
            God.                                  --Jer. Taylor.

   2. Existing in act or reality; really acted or acting; in
      fact; real; -- opposed to {potential}, {possible},
      {virtual}, {speculative}, {conceivable}, {theoretical}, or
      {nominal}; as, the actual cost of goods; the actual case
      under discussion.

   3. In action at the time being; now exiting; present; as the
      actual situation of the country.

   {Actual cautery}. See under {Cautery}.

   {Actual sin} (Theol.), that kind of sin which is done by
      ourselves in contradistinction to ``original sin.''

   Syn: Real; genuine; positive; certain. See {Real}.

Source : WordNet®

actual sin
     n : a sin committed of your own free will (as contrasted with
         original sin) [ant: {original sin}]