Source : Webster's Revised Unabridged Dictionary (1913)

Fallow \Fal"low\, v. t. [imp. & p. p. {Fallowed}; p. pr. & vb.
   n. {Fallowing}.] [From {Fallow}, n.]
   To plow, harrow, and break up, as land, without seeding, for
   the purpose of destroying weeds and insects, and rendering it
   mellow; as, it is profitable to fallow cold, strong, clayey
   land.