Of or relating to the river Pactolus (now Sart Çayı, in modern Turkey), formerly renowned for the gold which its sands contained. In later use: (chiefly figurative) golden; (of payment, funds, etc.) lavish, copious.
The legend of King Midas bathing in the river Pactolus to cure himself of his golden touch is recounted in Ovid Metamorphoses 11. 85ff.
Late 16th century; earliest use found in William Warner (d. 1609), poet and lawyer. From Pactolus (classical Latin Pactōlus, ancient Greek Πακτωλός), the name of a river in ancient Lydia which used to carry gold dust in its sands + -ian.