Nechtan

Celtic name of uncertain meaning, possibly meaning "damp" (cognate with NEPTUNE). In Irish mythology Nechtan was the husband of Boand, the goddess of the River Boyne. This name was also borne by the 5th-century Saint Nectan of Hartland in Devon, who was supposedly born in Ireland. It was also the name of several kings of the Picts.

NEPTUNE   male   Roman Mythology (Anglicized)
From the Latin Neptunus, which is of unknown meaning, possibly related to the Indo-European root *nebh "wet, damp, clouds". Neptune was the god of the sea in Roman mythology, approximately equivalent to the Greek god Poseidon. This is also the name of the eighth planet in the solar system.
EQUIVALENTS
ANCIENT CELTIC: Nechtan
IRISH MYTHOLOGY: Nechtan