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Hard Stop

A stop loss order that has been placed via the traders software package or with their broker ie it physicaly resides on either the trading software, the brokers servers or the exchange.

As opposed to a Mental Stop.

Quoting

A price level that, if reached, will trigger an order to sell an underlying security. Hard stops are set at a constant price and are inherently good until cancelled. A hard stop is used to protect the downside of holding an investment by always being active, and is only triggered once the price reaches the specified stop level.

Source for quote: https://www.investopedia.com/terms/h/hardstop.asp