n. a person worth many millions of dollars, pounds or some other currency
The Century Dictionary and Cyclopedia
n. One who possesses property worth several million dollars (or pounds, or francs, etc.).
Word Usage
"Alex writes about the Jew of Katanga; Moïse Katumbi Katebe Chapwe, a multimillionaire, is the powerful governor of the Province of Katanga, one of the mineral-rich Wild West zones of the Democratic Republic of Congo."