Nether means lower, or belonging to the world below. The nether regions, nether world, nether parts.
It survives mainly in fixed phrases and in place names — the Netherlands is the low lands — and the nether regions is a coy way of naming the lower body. The netherworld is the realm of the dead. Note that the word is Old English and simply means lower, with none of the mystery it has picked up.
1adjectivenetherLower, or belonging to the world below.
“In the old story, the hero travels down into the nether world to rescue his wife.”
nether is a quality of being lower.
Old English nithera means lower, from a root meaning down. Beneath and the Netherlands come from the same downward root.
Proto-Indo-European
*h₁én
Proto-Germanic
*niþer
Proto-West Germanic
*niþer
Old English
niþera — lower, under, lowest
Middle English
nether
English, today
nether
Built from
From Middle English nether, nethere, nithere, from Old English niþera (“lower, under, lowest”), from niþer, niþor (“below, beneath, down, downwards, lower, in an inferior position”), from Proto-West Germanic niþer, from Proto-Germanic niþer, niþra (“down”), from Proto-Indo-European h₁én, nei- (“in, down”). Cognates include Dutch neder, German nieder, lb nidder, Danish -, Norwegian - and Swedish ned (“down”), Danish -, Norwegian - and Swedish nedre (“lower”), Faroese - and Icelandic niður.
Etymology from Wiktionary, CC BY-SA