Cosmo I., Grand-duke of Tuscany, head of the Republic of Florence, of which he made himself absolute master, a post he held in defiance of all opposition, in order to secure the independence of the state he governed, as well as its internal prosperity (1519‒1574).
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Cosmas Indicopleustes * Cosmography