nether
adjective /ˈneðə(r)/
  /ˈneðər/
[only before noun] (literary or humorous)- lower- a person’s nether regions (= their genitals)
 Oxford Collocations DictionaryNether is used with these nouns:- reach
 Word OriginOld English nithera, neothera, of Germanic origin; related to Dutch neder- (found in compounds), neer, and German nieder, from an Indo-European root meaning ‘down’.