The name Maddison is a girl's name meaning "son of Maud". Maddison is ranked #357 on our popularity charts and is often added to user-created lists like Bitchy Girl Names and discussed in our forums with posts like "Girls Makeover - Two Middles".
From the experts:
While the traditionally spelled Madison has been among the most popular names in the 21st century, this version isn't exactly unpopular. Nevertheless, the second d is superfluous.