The Collaborative International Dictionary of English v.0.48:

Henhouse \Hen"house`\, n.; pl. Henhouses.
   A house or shelter for fowls.
   [1913 Webster]

WordNet (r) 3.0 (2006):

henhouse
    n 1: a farm building for housing poultry [syn: chicken coop,
         coop, hencoop, henhouse]