Source : Webster's Revised Unabridged Dictionary (1913)

Slip \Slip\, v. i. [imp. & p. p. {Slipped}; p. pr. & vb. n.
   {Slipping}.] [OE. slippen; akin to LG. & D. slippen, MHG.
   slipfen (cf. Dan. slippe, Sw. slippa, Icel. sleppa), and fr.
   OE. slipen, AS. sl[=i]pan (in comp.), akin to G. schleifen to
   slide, glide, drag, whet, OHG. sl[=i]fan to slide, glide,
   make smooth, Icel. sl[=i]pa to whet; cf. also AS. sl?pan,
   Goth. sliupan, OS. slopian, OHG. sliofan, G. schliefen,
   schl?pfen, which seem to come from a somewhat different root
   form. Cf. {Slope}, n.]
   1. To move along the surface of a thing without bounding,
      rolling, or stepping; to slide; to glide.

   2. To slide; to lose one's footing or one's hold; not to
      tread firmly; as, it is necessary to walk carefully lest
      the foot should slip.

   3. To move or fly (out of place); to shoot; -- often with
      out, off, etc.; as, a bone may slip out of its place.

   4. To depart, withdraw, enter, appear, intrude, or escape as
      if by sliding; to go or come in a quiet, furtive manner;
      as, some errors slipped into the work.

            Thus one tradesman slips away, To give his partner
            fairer play.                          --Prior.

            Thrice the flitting shadow slipped away. --Dryden.

   5. To err; to fall into error or fault.

            There is one that slippeth in his speech, but not
            from his heart.                       --Ecclus. xix.
                                                  16.

   {To let slip}, to loose from the slip or noose, as a hound;
      to allow to escape.

            Cry, ``Havoc,'' and let slip the dogs of war.
                                                  --Shak.

Source : WordNet®

slip
     n 1: a socially awkward or tactless act [syn: {faux pas}, {gaffe},
           {solecism}, {gaucherie}]
     2: a minor inadvertent mistake usually observed in speech or
        writing or in small accidents or memory lapses etc. [syn:
        {slip-up}, {miscue}, {parapraxis}]
     3: potter's clay that is thinned and used for coating or
        decorating ceramics
     4: a part (sometimes a root or leaf or bud) removed from a
        plant to propagate a new plant through rooting or grafting
        [syn: {cutting}]
     5: a young and slender person; "he's a mere slip of a lad"
     6: a place where a craft can be made fast [syn: {mooring}, {moorage},
         {berth}]
     7: an accidental misstep threatening (or causing) a fall; "he
        blamed his slip on the ice"; "the jolt caused many slips
        and a few spills" [syn: {trip}]
     8: a slippery smoothness; "he could feel the slickness of the
        tiller" [syn: {slickness}, {slick}, {slipperiness}]
     9: artifact consisting of a narrow flat piece of material [syn:
         {strip}]
     10: a small sheet of paper; "a receipt slip" [syn: {slip of
         paper}]
     11: a woman's sleeveless undergarment [syn: {chemise}, {shimmy},
          {shift}, {teddies}, {teddy}]
     12: bed linen consisting of a cover for a pillow; "the burglar
         carried his loot in a pillowcase" [syn: {case}, {pillowcase},
          {pillow slip}]
     13: an unexpected slide [syn: {skid}, {sideslip}]
     14: a flight maneuver; aircraft slides sideways in the air [syn:
          {sideslip}]
     15: the act of avoiding capture (especially by cunning) [syn: {elusion},
          {eluding}]
     [also: {slipping}, {slipped}]

slipping
     adj : moving as on a slippery surface; "his slipping and
           slithering progress over the ice" [syn: {slithering}]

slip
     v 1: move stealthily; "The ship slipped away in the darkness"
          [syn: {steal}]
     2: insert inconspicuously or quickly or quietly; "He slipped
        some money into the waiter's hand"
     3: move obliquely or sideways, usually in an uncontrolled
        manner; "the wheels skidded against the sidewalk" [syn: {skid},
         {slue}, {slew}, {slide}]
     4: get worse; "My grades are slipping" [syn: {drop off}, {drop
        away}, {fall away}]
     5: move smoothly and easily
     6: to make a mistake or be incorrect [syn: {err}, {mistake}]
     7: pass on stealthily; "He slipped me the key when nobody was
        looking" [syn: {sneak}]
     8: pass out of one's memory [syn: {slip one's mind}]
     9: move out of position; "dislocate joints"; "the artificial
        hip joint luxated and had to be put back surgically" [syn:
         {dislocate}, {luxate}, {splay}]
     [also: {slipping}, {slipped}]

slipping
     See {slip}