"an emperor, a ruler, a dictator," late 14c., cesar , from Cæsar , originally a surname of the Julian gens in Rome, elevated to a title after Caius Julius Caesar (100 B.C.E.-44 B.C.E.) became dictator; it was used as a title of emperors down to Hadrian (138 C.E.). The name is of uncertain origin; Pliny derives it from caesaries "head of hair," because the future dictator was born with a full one; Century Dictionary suggests Latin caesius "bluish-gray" (of the eyes), also used as a proper name. Also compare caesarian .

Old English had casere , which would have yielded modern *coser , but it was replaced in Middle English by keiser (c. 1200), from Norse or Low German, and later by the French or Latin form of the name. Cæsar 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 .

The use in reference to "temporal power as the object of obedience" (contrasted with God ) is from Matthew xxii.21. Caesar's wife (1570s) as the figure of a person who should be above suspicion is from Plutarch. In U.S. slang c. 1900, a sheriff was Great Seizer .

late 14c., seccioun , in astronomy, "the intersection of two straight lines; a division of a scale;" from Old French section and directly from Latin sectionem (nominative sectio ) "a cutting, cutting off, division," noun of action from past-participle stem of secare "to cut" (from PIE root *sek- "to cut").

?The meaning "a part cut off or separated from the rest" is from early 15c. That of "a drawing representing something as if cut through" is from 1660s. From 1550s in English in the meaning "act of cutting or dividing," a sense now rare or archaic and preserved in some medical phrases, most notably Caesarian section . The meaning "a subdivision of a written work, statute, etc." is from 1570s.

Books are commonly divided into Chapters , Chapters into Sections , and Sections into Paragraphs or Breaks , as Printers call them .... [Blount, "Glossigraphia," 1656]

In music, "a group of similar instruments in a band or orchestra" (1880). In U.S. history, a square of 640 acres into which public lands were divided (1785). In World War II U.S. military slang, section eight was a reference to the passage in an Army Regulations act that referred to discharge on grounds of insanity.