\Laugh"ter\, n. [AS. hleahtor; akin to OHG. hlahtar, G.
gel["a]chter, Icel. hl[=a]tr, Dan. latter. See {Laugh}, v. i.
]
A movement (usually involuntary) of the muscles of the face,
particularly of the lips, with a peculiar expression of the
eyes, indicating merriment, satisfaction, or derision, and
usually attended by a sonorous and interrupted expulsion of
air from the lungs. See {Laugh}, v. i.

      The act of laughter, which is a sweet contraction of
      the muscles of the face, and a pleasant agitation of
      the vocal organs, is not merely, or totally within the
      jurisdiction of ourselves.               --Sir T.
                                               Browne.

      Archly the maiden smiled, and with eyes overrunning
      with laughter.                           --Longfellow.