very wealthy person; millionaire
Refers to a person of great wealth, often with a nuance of being a plutocrat or someone who flaunts their riches. Slightly literary or formal.
He became a millionaire in one generation.
That wealthy person lives in a mansion.
大金持ち is a casual, straightforward term for a very rich person, whereas 金満家 is more literary and may imply a critical view of wealth.
Compound of 金 (money, gold), 満 (full, satisfy), and 家 (person, specialist). The exact historical derivation is uncertain, but the term literally suggests a person 'full of money'.