den: [OE] Related forms such as German tenne ‘threshing floor’ and possibly Greek thenar ‘palm of the hand’ suggest that the underlying meaning of den may be ‘flat area’. Old English denn denoted ‘wild animal’s lair’, perhaps with reference to animals’ flattening an area of vegetation to form a sleeping place. Dean [OE], a word for ‘valley’ now surviving only in placenames, comes from the same source.
