The term 'Nether Regions' is a phrase used to refer to the underworld, HELL, and other dark and mysterious places. It can also be used to refer to the DEPTHS of the human body, such as the loins. The crossword solutions for this term are 'Underworlds' (11 letters), 'HELL' (4 letters), 'DEPTHS' (6 letters), and 'Loins' (5 letters). All of these words refer to dark and mysterious places, either literal or figurative.