“We want to replace decimal numeration by dozenal,” is the aim of the Dozenal Society of Great Britain. That will give you the necessary clue to its meaning — it’s from the word dozen and it refers to a system of counting by twelves. You’re much more likely to be familiar with the well-established duodecimal. If you did New Maths as a child you might also remember base 12.
In a dozenal system, with counting based on twelve, not ten, the number “100” would mean 144 in our base-ten counting system, and twelve “dozades” (each twelve years long) would make up a grossury, with 144 decimal years.
Coast Lines, by Mark S Monmonier, 2008.
Dozenal is a rare adjective (sometimes a noun for an advocate of the numbering system) that’s absent from every dictionary on my shelves, though it does appear occasionally in technical literature as well as in reports about the system:
Dozenals contend much of life already is divided into twelves: People buy dozens of eggs and dozens of doughnuts. There are 12 months in the year and 12 inches to a foot.
Los Angeles Times, 17 May 1982.
Any popularity it has would seem to be the result of its adoption in its title about a couple of decades ago by the Dozenal Society of America (the successor to the old Duodecimal Society of America) and by its British cousin.
An enthusiast for the duodecimal number system has been called a dozenalist or a dozener. Neither is at all common.