GNU Collaborative International Dictionary of English

Found 2 definitions

1.       
   Lean-to (?), a. (Arch.) Having only one slope or pitch; -- said of a roof.
   
   [1913 Webster]
   
   
         
       

2.       
   Lean-to (?), n.
   1. (Arch.) A shed or slight building placed against the wall of a larger structure and having a single-pitched roof; -- called also penthouse, and to-fall.
   
   [1913 Webster]
   
   The outer circuit was covered as a lean-to, all round this inner apartment. De Foe.
   
   [1913 Webster]
   
   
   2. A crude, usually temporary shelter comprising a lean-to roof braced against any convenient support, as a wall, a tree or a pole. The roof may extend all the way to the ground.
   
   [PJC]