The Collaborative International Dictionary of English v.0.48:

Glide \Glide\, v. i. [imp. & p. p. Glided; p. pr. & vb. n.
   Gliding.] [AS. gl[imac]dan; akin to D. glijden, OHG.
   gl[imac]tan, G. gleiten, Sw. glida, Dan. glide, and prob. to
   E. glad.]
   [1913 Webster]
   1. To move gently and smoothly; to pass along without noise,
      violence, or apparent effort; to pass rapidly and easily,
      or with a smooth, silent motion, as a river in its
      channel, a bird in the air, a skater over ice.
      [1913 Webster]

            The river glideth at his own sweet will.
                                                  --Wordsworth.
      [1913 Webster]

   2. (Phon.) To pass with a glide, as the voice.
      [1913 Webster]

   3. (A["e]ronautics) To move through the air by virtue of
      gravity or momentum; to volplane.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

gliding
    n 1: the activity of flying a glider [syn: glide, gliding,
         sailplaning, soaring, sailing]