Means ‘Sea-wanderer’.

Aerandir was one of the three mariners who accompanied Eärendil on his voyages. Most notably, he was there when Eärendil and Elwing completed their voyage to the Undying Lands with one of the Silmarils.

There, Eärendil and Elwing departed and they were taken from their people forever. We can only assume that Aerandir was allowed to return to Middle-earth, but there is no written evidence of this, or otherwise.
Encyclopedia entry originally written by Nienna-of-the-Valar