The Collaborative International Dictionary of English v.0.48:

Coomb \Coomb\, n. [AS. cumb a liquid measure, perh. from LL.
   cumba boat, tomb of stone, fr. Gr. ? hollow of a vessel, cup,
   boat, but cf. G. kumpf bowl.]
   A dry measure of four bushels, or half a quarter. [Written
   also comb.]
   [1913 Webster] Coomb

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]