Partook is the past tense of the verb partake, which means to take part in something or to have a share of something.

When someone partook in an activity, they participated in it. If you partook in your school's science fair, you entered a project and joined the event. When guests partook of a meal, they ate some of the food that was offered. A character in a historical novel might partake of tea and biscuits with friends.

The word has a somewhat formal or old-fashioned ring to it. You're more likely to see it in books than hear it in everyday conversation. Instead of saying “I partook in the game,” most people today would simply say “I took part in the game” or “I played the game.” Instead of “They partook of the feast,” we'd usually say “They ate at the feast.”

Still, partook appears often enough in literature and formal writing that it's useful to recognize. When you see that someone partook of something, they either participated in an activity or consumed some portion of food or drink that was available.