Source : Webster's Revised Unabridged Dictionary (1913)

Hectare \Hec"tare`\, n. [F., fr. Gr. ? hundred + F. are an are.]
   A measure of area, or superficies, containing a hundred ares,
   or 10,000 square meters, and equivalent to 2.471 acres.

Source : WordNet®

hectare
     n : (abbreviated `ha') a unit of surface area equal to 100 ares
         (or 10,000 square meters)