Caesar

Gaius
[gey-uh s] /ˈgeɪ əs/ (Show IPA), (or Caius)
[key-uh s] /ˈkeɪ əs/ (Show IPA), Julius, c100–44 b.c, Roman general, statesman, and historian.
Sidney (“Sid”) 1922–2014, U.S. comedian.
a title of the Roman emperors from Augustus to Hadrian, and later of the heirs presumptive.
any emperor.
a tyrant or dictator.
any temporal ruler, in contrast with God; the civil authority. Matt. 22:21.
a male given name: from a Roman family name.
either a Caesar or nothing; all or nothing.
Contemporary Examples

Slow Eating and Weight Loss: Does the Science Support It? Susan B. Roberts March 16, 2011
Could Andy Serkis Win an Oscar for Planet of the Apes? Marlow Stern December 21, 2011
Syrian Defector: Assad Poised to Torture and Murder 150,000 More Josh Rogin July 30, 2014
Motion Capture Maestro Andy Serkis on ‘Dawn of the Planet of the Apes’ and Revolutionizing Cinema Marlow Stern July 7, 2014
How America Started The Border Crisis Eleanor Clift July 24, 2014

Historical Examples

A Thorny Path [Per Aspera], Complete Georg Ebers
The Man Shakespeare Frank Harris
A Thorny Path [Per Aspera], Complete Georg Ebers
The Man Shakespeare Frank Harris
Ancient Rome Mary Agnes Hamilton

noun
Gaius Julius (ˈɡaɪəs ˈdʒuːlɪəs). 100–44 bc, Roman general, statesman, and historian. He formed the first triumvirate with Pompey and Crassus (60), conquered Gaul (58–50), invaded Britain (55–54), mastered Italy (49), and defeated Pompey (46). As dictator of the Roman Empire (49–44) he destroyed the power of the corrupt Roman nobility. He also introduced the Julian calendar and planned further reforms, but fear of his sovereign power led to his assassination (44) by conspirators led by Marcus Brutus and Cassius Longinus
any Roman emperor
(sometimes not capital) any emperor, autocrat, dictator, or other powerful ruler
a title of the Roman emperors from Augustus to Hadrian
(in the Roman Empire)

a title borne by the imperial heir from the reign of Hadrian
the heir, deputy, and subordinate ruler to either of the two emperors under Diocletian’s system of government

short for Caesar salad

Note: The emperors of Germany and Russia in modern times adapted the word caesar into titles for themselves — kaiser and czar.