Source : Webster's Revised Unabridged Dictionary (1913)

Lapse \Lapse\, v. i. [imp. & p. p. {Lapsed}; p. pr. & vb. n.
   {Lapsing}.]
   1. To pass slowly and smoothly downward, backward, or away;
      to slip downward, backward, or away; to glide; -- mostly
      restricted to figurative uses.

            A tendency to lapse into the barbarity of those
            northern nations from whom we are descended.
                                                  --Swift.

            Homer, in his characters of Vulcan and Thersites,
            has lapsed into the burlesque character. --Addison.

   2. To slide or slip in moral conduct; to fail in duty; to
      fall from virtue; to deviate from rectitude; to commit a
      fault by inadvertence or mistake.

            To lapse in fullness Is sorer than to lie for need.
                                                  --Shak.

   3. (Law)
      (a) To fall or pass from one proprietor to another, or
          from the original destination, by the omission,
          negligence, or failure of some one, as a patron, a
          legatee, etc.
      (b) To become ineffectual or void; to fall.

                If the archbishop shall not fill it up within
                six months ensuing, it lapses to the king.
                                                  --Ayliffe.

Source : WordNet®

lapsing
     n : a failure to maintain a higher state [syn: {backsliding}, {lapse},
          {relapse}, {relapsing}, {reversion}, {reverting}]