Origin and history of prex

late 14c., "one who presides over the meetings of an executive or a governing or judicial body;" also "a ruler," either sovereign or subordinate, especially in reference to judicial powers; from Old French president and directly from Latin praesidentum (nominative praesidens) "president, governor," noun use of present participle of praesidere "to act as head or chief" (see preside). Also in Middle English in reference to heads of religious houses, hospitals, almshouses, colleges and universities.

The use for "chief executive officer of a republic" in the U.S. Constitution (1787), is from earlier American use for "officer in charge of the Continental Congress" (1774), still earlier in individual colonies (Virginia, 1608), a republican sense derived from that of "chosen head of a meeting or group of persons." In the constitutions of 1776 Delaware, New Hampshire, and South Carolina gave the title president to their chief magistrates in place of governor (Pennsylvania did away with the position entirely) but eventually reverted to governor.

It had been used of chief officers of banks from 1781. The slang shortening prez is recorded from 1883. Fem. form presidentess is attested from 1763.

1871, college slang, an extension or diminutive of prex.

slang shortening of president, 1892, American English. Compare prex.