Mairon, masc. name "the Admirable" (cf. adj. maira), said to be the original name of Sauron, changed when he was suborned by Melkor, "but he continued to call himself Mairon the Admirable, or Tar-mairon King Excellent, until after the downfall of Númenor" (PE17:183). Since Sauron had joined Melkor before the Elves came to Valinor and developed the Quenya language, we are perhaps to understand that Mairon is a translation by sense of Saurons original Valarin name, though Sauron himself may seem to have used the Elvish form in Middle-earth and on Númenor.
Quenya
mairon
masculine name. Admirable
Mairon
the admirable
Mairen
well
Mairen fem. name(UT:210), initial element perhaps related or identical to mai "well". The second element is obscure; the root REN "recall, have in mind" (PM:372) could be related; if so the name may imply "well remembered", "(of) good memory" or something similar. It may also connect with the adj. maira, q.v. and compare the masc. name Mairon (PE18:163).
maira
admirable, excellent, precious
maira adj. "admirable, excellent, precious"; "splendid, sublime" ("only of great, august or splendid things") (PE17:163, 172). Cf. Mairon.
Sauro
the abhorred
Sauro (þ) (1), usually in longer form Sauron (þ), masc. name "the Abhorred", name of a Maia, the second Dark Lord (said to be the name by which he was "afterwards called", MR:147; according to PE17:183, his original name was Mairon, q.v.). Earlier Thauron (SA:thaur, THUS), archaic *Θaurond- (Letters:380, where the initial Greek letter represents th). The stem of Sauron* would then be Saurond-. Another form of the name is Súro**.
ehtelu-
verb. well, bubble out
mai
well
mai (1) adv. "well" (VT47:6), apparently also used as prefix (PE17:17:162, 163, 172)
mai
adverb. well, well; [ᴱQ.] too much
mandë
well
mandë (2) adv. "well" (VT49:26; this is "Qenya"). Rather mai in Tolkiens later Quenya.
tampo
well
tampo noun "well" (QL:93)
tampo
noun. well
The original name of Sauron before his corruption by Melkor (PE17/183). Even after his corruption, he still called himself Mairon or Tar-Mairon sometimes, at least until he lost his beautiful form after the fall of Númenor (PE17/183). This name seems to be a masculinized form of the adjective maira “admirable”.