Those cooking up the United States naval hull classification system were trying to be sensible. After all, B means battleship, C means cruiser, D means destroyer and S means submarine.
So why are aircraft carriers labeled CV?
When the mighty ships were first coming into use they were considered cruisers hence the C and things would be flown off it hence the V.
OK, the V. It’s based on the French word voler which means to fly. Why French? We don’t know. Guess it made sense at the time.