Caesar

"delivery of a child by cutting through the abdomen of the mother," 1923, shortening of Caesarian section (1610s); caesar as "baby delivered by caesarian section is from 1530s. Section (n.) here has the literal Latin sense of "act or action of cutting," which is attested from 1550s in English but is rare outside of medicine.

Supposedly from Caius Julius Caesar, who was said to have been delivered surgically. Thus also legend traces his cognomen to Latin caesus, past participle of caedere "to cut" (see -cide). But if this is the etymology of the name, it was likely an ancestor who was so born (Caesar's mother lived to see his triumphs and such operations would have been fatal to the woman in ancient times). Rather, caesar here may come directly from caesus.

The operation was prescribed in Rome for cases of dead mothers; the first recorded instance of it being performed on a living woman is c. 1500, but as late as the early 19c., before antiseptics and blood transfusions, it had a 50% mortality rate.

the common title of the emperor of Russia, 1550s, from Russian tsar, from Old Slavic tsesari, from Gothic kaisar, from Greek kaisar, from Latin Caesar. First adopted by Russian emperor Ivan IV, 1547.

The spelling with cz- is against the usage of all Slavonic languages; the word was so spelt by Herberstein, Rerum Moscovit. Commentarii, 1549, the chief early source of knowledge as to Russia in Western Europe, whence it passed into the Western Languages generally; in some of these it is now old-fashioned; the usual Ger. form is now zar; French adopted tsar during the 19th c. This also became frequent in English towards the end of that century, having been adopted by the Times newspaper as the most suitable English spelling. [OED]

The Germanic form of the word also is the source of Finnish keisari, Estonian keisar. The transferred sense of "person with dictatorial powers" is first recorded 1866, American English, initially in reference to President Andrew Johnson. The fem. czarina is 1717, from Italian czarina, from Ger. Zarin, fem. of Zar "czar." The Russian fem. form is tsaritsa. His son is tsarevitch, his daughter is tsarevna.