What does “une tenue” mean in French?

Une tenue is an outfit: the whole set of clothes put together for an occasion — une tenue de sport, une tenue de soirée, une tenue de motard. It comes from tenir, “to hold,” and the older sense lives on beside the clothes one: avoir de la tenue is about bearing and good manners. The sign tenue correcte exigée on a restaurant door is the clothing sense, asking you to dress properly.

That “holding” idea reaches one step further. La tenue d’une réunion or la tenue du festival is the fact of the event taking place — the holding of it. So a single noun covers what you put on, how you carry yourself, and whether something goes ahead, all from the same root.