Originally they were MOON-ths. Then someone decided their calanders just had to be systematic, organized, and set up to comply with idealist principles rather than the reality of nature seen before one's eyes. Someone came up with the stupid idea that the solar years ideally SHOULD have 360 days of 12 Moonths each exactly 30 days long. Reality bites idealism every time.

To me a month is the length of time from one full moon to the next fully moon. That length can vary in actual number of solar days, does not matter, its still a month. But then what do I know, I just the 1/100th gram piss ant in the room.