Source : Webster's Revised Unabridged Dictionary (1913)

Lough \Lough\, n. [See 1st {Loch}.]
   A loch or lake; -- so spelt in Ireland.

Lough \Lough\, obs. strong imp.
   of {Laugh}. --Chaucer.

Source : WordNet®

lough
     n 1: a long narrow (nearly landlocked) cove in Ireland
     2: Irish word for a lake