A firm quote is a quote displayed at which the market maker is obligated to buy or sell at the quoted price.
A firm quote includes a bid and ask price at which a market maker is willing to trade a specific quantity.
A firm quote is non-negotiable. It is a “take it or leave it” offer.
With a firm quote, the price is guaranteed. Market makers are obliged to deal at the displayed price and volume when their quotes are firm.