dorman tree

from The Collaborative International Dictionary of English v.0.48

Dormant \Dor"mant\, n. [See {Dormant}, a.] (Arch.)
   A large beam in the roof of a house upon which portions of
   the other timbers rest or " sleep." --Arch. Pub. Soc. --
   Called also {dormant tree}, {dorman tree}, {dormond}, and
   {dormer}. --Halliwell. Dormer