Eldest son of Fëanor (S/60). His name is an adaption of elements from both his mother-name Q. Maitimo “Well-shaped One” and his nickname Q. Russandol “Copper-top”: S. maed¹ “shapely” and S. ross² “red-haired” (PM/366). As such, his name was perhaps more properly spelled Maedros (PM/352).
Conceptual Development: When he first appeared in the earliest Lost Tales, this character’s name was G. Maidros (LT2/241), a name that earlier in the tales was used for the grandfather of Fëanor (LT1/146). This form continued to be used in the Silmarillion drafts from the 1930s (SM/88, LR/223), but in The Etymologies, Tolkien said it was an anglicanization of proper Noldorin Maidhros “Pale-glitter” (Ety/MAD), which also appeared in The Etymologies as N. Maedhros (Ety/RUS).
The form Maidhros continued to appear in Silmarillion revisions from the 1950s-60s (WJ/115), but for the most part earlier Maidros was revised to Maedhros (MR/177), the form Christopher Tolkien adopted for the published version of The Silmarillion: see N. [ai] revised to [ae]. Tolkien constructed the derivation given above in the “Shibboleth of Fëanor”, where he actually used the form Maedros (PM/352, 366). Later still he considered revising the name to Maedron (PM/372, note #2), but this change was not carried out in the texts.