Dictionary of Ichthyology  

kettle hole = a depression found in glacial deposits where a piece of ice from a retreating glacier became embedded in soft glacial till or drift. These holes are often filled with water making a small pond or lake.

Highlands of Isunngua, Greenland, from Wikimedia Commons: http://en.wikipedia.org/wiki/File:Kettle-glacial-lake-form-isunngua-greenland.jpg

Canadian Museum of Nature