Name of the “Doors of Night” leading beyond the world in Silmarillion drafts from the 1930s (SM/237, 241), also appearing as a rejected name in The Etymologies as combination of ando “door” and the genitive of lóme “night” (EtyAC/LOƷ).
Qenya
-ando
suffix. agent (male)
ando
adverb. long
hando
noun. agent (male)
anda
adjective. long
ando lómen
proper name. Door of Night
An adverbial form of anda “long” from the phrase Q. Eldar ando kakainen loralyar Koivienenissen “the Elves were long lying asleep at Koivienéni” (VT27/7).