In french there's also the curious case of "pesanteur" (gravity), which is feminine; so "la pesanteur" (the gravity). But the absence of gravity is "apesanteur" (weightlessness), which is also a feminine word; so "l'apesenteur". So we have two slightly different words that actually sound exactly the same with their articles. It's only a few years ago that people decided to change the prefix and use "impesanteur" instead (which is however a bit less accurate - see the difference between "im-possible" (not possible) and "a-gnostic" (without belief)).