(‘fixed price’ in French)
Prix fixe refers to a multi-course meal served for a set price. Specific courses are often pre-selected by the restaurant; in some cases diners are allowed to make choices and substitutions.
Prix fixe is the opposite of à la carte, the system in which a diner chooses individually priced items from a menu and pays for them accordingly. Many restaurants offer both prix fixe and à la carte options.
Note: most U.S. publications do not use a hyphen (contrary to the general rule for compound adjectives) when using prix fixe as an adjective: prix fixe lunch, prix fixe menu, etc.
I considered ordering à la carte, but the prix fixe options turned out to be cheaper.