Smith's Dictionary
(sarac or sareca, only used (Daniel 6:1) ... the Chaldee equivalent for Hebrew shter, probably from sara, Zend. a “head”), a high officer in the Persian court, a chief, a president, used of the three highest ministers.
International Standard Bible Encyclopedia
prez'-i-dent (carakh): Used only in Da 6:2-7. Probably a Persian derivative from sar, "head," and the Aramaic equivalent for Hebrew shoter. The meaning is self-evident and refers to the appointment of Daniel by Darius to be one of the three princes who had rule over the satraps of the empire.