§ Of Maeglin The Silmarillion

It is not said that Aredhel was wholly unwilling, nor that her life in Nan Elmoth was hateful to her for many years. For though at Eöl's command she must shun the sunlight, they wandered far together under the stars or by the light of the sickle moon; or she might fare alone as she would, save that Eöl forbade her to seek the sons of Fëanor, or any others of the Noldor. And Aredhel bore to Eöl a son in the shadows of Nan Elmoth, and in her heart she gave him a name in the forbidden tongue of the Noldor, Lómion, that signifies Child of the Twilight; but his father gave him no name until he was twelve years old. Then he called him Maeglin, which is Sharp Glance, for he perceived that the eyes of his son were more piercing than his own, and his thought could read the secrets of hearts beyond the mist of words.