Source : Webster's Revised Unabridged Dictionary (1913)

Freewheel \Free"wheel`\, v. i.
   1.
      (a) Of a freewheel cycle, to run on while the pedals are
          held still.
      (b) Of a person, to ride a cycle of this manner. To ride a
          freewheel cycle.

   2. (Mach.) To operate like a freewheel, so that one part
      moves freely over another which normally moves with it; --
      said of a clutch.

Freewheel \Free"wheel`\, n. (Mach.)
   A clutch fitted in the rear hub of a cycle, which engages the
   rear sprocket with the rear wheel when the pedals are rotated
   forwards, but permits the rear wheel to run on free from the
   rear sprocket when the pedals are stopped or rotated
   backwards. Freewheelcycles are usually fitted with hub brakes
   or rim brakes, operated by back pedaling.

Source : WordNet®

freewheel
     n : a clutch (as on the rear wheel of a bicycle) that allows
         wheels to turn freely (as in coasting)
     v 1: live unhurriedly, irresponsibly, or freely; "My son drifted
          around for years in California before going to law
          school" [syn: {drift}]
     2: coast in a vehicle using the freewheel