Source : Webster's Revised Unabridged Dictionary (1913)

Thatcher \Thatch"er\, n.
   One who thatches.

Source : WordNet®

Thatcher
     n 1: British stateswoman; first woman to serve as Prime Minister
          (born in 1925) [syn: {Margaret Thatcher}, {Margaret
          Hilda Thatcher}, {Baroness Thatcher of Kesteven}, {Iron
          Lady}]
     2: someone skilled in making a roof from plant stalks or
        foliage