Other forms: predetermined; predetermining; predetermines
The verb predetermine means "determine in advance," like when you predetermine how much money you will spend on your friend's birthday present to make shopping easier.
Predetermine comes from the Latin word praedeterminare, from prae, meaning “beforehand,” and determinare, meaning “limit, settle.” When you predetermine things, such as who will bring the food and music to a party, things run more smoothly than if you left it to chance. Another meaning of the word isn't so positive — if the organizers of a contest predetermine that their friend will win, this isn't fair to the other participants.