cognomen of the third Roman emperor (12 C.E.-41 C.E.), born Gaius Caesar. The nickname is Latin, literally "little boot," given when he joined his father on military campaigns when still a toddler, in full, child-sized military gear; diminutive of caliga "heavy military shoe," of unknown origin.
c.1200, see caesarian; Old English had casere, which would have yielded modern *coser, but it was replaced in Middle English by keiser, from Norse or Low German, and later in Middle English by the French or Latin form of the name. Cæsar was used as a title of emperors down to Hadrian (138 C.E.), and also is the root of German Kaiser and Russian tsar (see czar). He competes as progenitor of words for "king" with Charlemagne (Latin Carolus), as in Lithuanian karalius, Polish krol. In U.S. slang c.1900, a sheriff was Great Seizer.