Used for amounts, prices, competition, or demands that go beyond what is reasonable or appropriate. Often appears in formal or business contexts.
We cannot accept excessive demands.
I think this price is exorbitant.
That hotel demanded an exorbitant fee.
Competition in the market has become excessive.
法外 carries a stronger, more emotional sense of being outrageously beyond normal limits, while 過当 is a calmer, more formal way of saying something exceeds a reasonable standard.
適正 describes an amount, price, or level that is fair and appropriate, the opposite of 過当, which describes one that is excessive and unreasonable.
excessive competition; cutthroat competition
Compound of 過 (exceed) and 当 (appropriate), literally 'exceeding what is proper'.