A millionaire has a net worth of at least one million in the relevant currency. A multimillionaire has several million — the prefix means "more than one", so there is no exact threshold, though it usually implies comfortably more than two. Above that sit centimillionaire (a hundred million) and billionaire.
The core difference
Both are wealth labels; only the first has a definable line.
- millionaire — net worth of at least one million.
- multimillionaire — several million; no fixed threshold.
- centimillionaire — around a hundred million.
- billionaire — a thousand million.
What counts as the million
Usually net worth — assets minus liabilities — rather than income or a single asset. Whether a primary residence is included varies by source, which is why wealth reports often specify "excluding primary residence" and why counts of millionaires differ so widely between them.
The word
Millionaire came into English from French in the early eighteenth century, and by the nineteenth the ordinary word was no longer impressive enough — hence multimillionaire, and eventually billionaire. The vocabulary has inflated alongside the fortunes.
