You can use the noun outfit to mean clothes that go together, like a shirt and pants that you always wear to job interviews. You might have spent hours choosing your first-day-of-school outfit.
An outfit is often selected for a special occasion, like a graduation outfit, an outfit for your cousin's party, or your rodeo outfit. An outfit is also a kit or set of tools that serve a specific purpose, and as a verb it means "provide with" or "equip." A girl scout leader, for example, will outfit her troops with water and sunblock for a long hike on a sunny summer day.