A companion of Eärendil (S/248).
Conceptual Development: In Silmarillion drafts from the 1930s, his name was given as N. Airandir (LR/324), changed to Aerandir in revisions from the 1950s-60s (WJ/246).
Possible Etymology: The second element of this name is very likely S. randir “wanderer” (SA/ran), but the meaning of the initial element is unclear. Christopher Tolkien translated this name as “Sea-wanderer” in The Silmarillion index (SI/Aerandir). If correct, the initial element is probably some form of S. gaear “sea”. This is problematic, since in J.R.R. Tolkien’s late writings this word usually (but not always) began with a g, which would have no reason to vanish in the initial position.
The Noldorin form of this name was Airandir. In The Etymologies, the Noldorin word for “sea” was N. oer (Ety/AY). Noldorin [oe] sometimes appeared as [ai] in names from earlier narratives. For example, compare (ᴱN.) Aiglir Angrin “Iron Mountains” from the 1920s and early 1930s (SM/220) to [N.] oeglir “range of mountain peaks” in The Etymologies (Ety/AYAK), and later still (S.) aeglir “line of peaks” (RC/11). Perhaps Tolkien originally intended this element to mean “sea”, updating it phonetically ([[n|[ai] revised to [ae]]]) in later Silmarillion revisions without considering a change in meaning.
Absent any further evidence, “Sea-wanderer” remains the best available translation.
aer, aear (“sea”) + randír (“wanderer, pilgrim”)