Source : Webster's Revised Unabridged Dictionary (1913)

Glyn \Glyn\, Glynne \Glynne\, n.
   A glen. See {Glen}.

   Note: [Obs. singly, but occurring often in locative names in
         Ireland, as Glen does in Scotland.]

               He could not beat out the Irish, yet he did shut
               them up within those narrow corners and glyns
               under the mountain's foot.         --Spenser.