A fortress on the river Sirion, translated “Tower of the Well” (S/191). It is a combination of barad “tower” and eithel “spring, (water) source” (SA/barad, eithel).
Sindarin
Barad Eithel
noun. tower of [the] well
barad eithel
place name. Tower of the Well
Elements
Word Gloss barad “tower, great towering building, tower, great towering building, [N.] fort, fortress” eithel “source, spring, well, source, spring, well, [N.] issue of water, fountain”
barad (“tower”) + eithel (“spring, well”)