The Collaborative International Dictionary of English v.0.48:

Comb \Comb\, Combe \Combe\ (? or ?), n. [AS. comb, prob. of
   Celtic origin; cf. W. cwm a dale, valley.]
   That unwatered portion of a valley which forms its
   continuation beyond and above the most elevated spring that
   issues into it. [Written also coombe.] --Buckland.
   [1913 Webster]

         A gradual rise the shelving combe
         Displayed.                               --Southey.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Coomb \Coomb\, Coombe \Coombe\, n. [See Comb, Combe, in this
   sense.]
   A hollow in a hillside. [Prov. Eng.] See Comb, Combe.
   [1913 Webster]