The Collaborative International Dictionary of English v.0.48:
Boathouse \Boat"house`\, n. A house for sheltering boats. [1913 Webster] Half the latticed boathouse hides. --Wordsworth. [1913 Webster]WordNet (r) 3.0 (2006):
boathouse n 1: a shed at the edge of a river or lake; used to store boats