Tar-Aldarion's royal name signifies "Son of the trees" (alda + -ion) because he was a noted tree steward and forester — trees were essential to the construction of his fleets, but he took great care to replenish what was being felled.
Quenya
aldarion
masculine name. *Son of Trees
tar-aldarion
Tar-Aldarion
Tar-Aldarion was the name assumed by the sixth ruler of Númenor (LotR/1038, UT/219). His name seems to be a compound aldar “trees” and the patronymic suffix -ion “-son”. He adoped this name “because he was much concerned with trees, and planted great woods to furnish timber for the shipyards” (UT/219).