[1] : The Collaborative International Dictionary of English v.0.48

summerhouse \sum"merhouse`\, n.; pl. summerhouses.
   a rustic house or apartment in a garden or park, to be used
   as a pleasure resort in summer. --shak.
   1913 webster
see also:
summerhouses 

[2] : WordNet (r) 2.0

summerhouse
     n : a small roofed building affording shade and rest syn: gazebo
see also:
gazebo 

[3] : Moby Thesaurus II by Grady Ward, 1.0

25 moby thesaurus words for "summerhouse":
   alcove, arbor, belvedere, bower, cloche, cold frame, conservatory,
   coolhouse, forcing bed, forcing house, forcing pit, gazebo,
   glasshouse, greenhouse, hotbed, hothouse, kiosk, lathhouse,
   nursery, orangery, pagoda, pergola, pinery, retreat, seedbed

Summerhouse >> S Words
Summerhouse, definition of term: Summerhouse
summerhouse_pag1.html