also pleb, "member of the lowest class at a U.S. military academy," 1833, probably a shortened form of plebeian "one of the lower class," which in Latin had also the short form plebs or plebes.
"of or characteristic of the lower class or the common people," 1560s in a Roman historical sense, from Latin plebeius "belonging to the plebs," earlier plebes, "the populace, the common people" (as opposed to patricians, etc.), also "commonality; the mass, the multitude; the lower class" (from PIE *ple-, from root *pele- (1) "to fill"). In general (non-historical) use from 1580s.
"direct vote of the people, an expression of the will or pleasure of the whole people in regard to some matter already decided upon," 1852 (originally in English in reference to France), from French plébiscite (1776 in modern sense, originally with reference to Switzerland), from Latin plebiscitum "a decree or resolution of the people," from plebs (genitive plebis) "the common people" (see plebeian (adj.)) + scitum "decree," noun use of neuter past participle of sciscere "to assent, vote for, approve," inchoative of scire "to know" (see science). Used earlier (1530s) in a purely historical context, "law enacted in ancient Rome by the lower rank of citizens, meeting in assembly under the presidency of a plebeian magistrate." The word was attested earlier in a purely classical context. Related: Plebiscitary.
1640s, "an unprincipled popular orator or leader; one who seeks to obtain political power by pandering to the prejudices, wishes, ignorance, and passions of the people or a part of them," ultimately from Greek dēmagōgos "popular leader," also "leader of the mob," from dēmos "people, common people" (originally "district," from PIE *da-mo- "division," from root *da- "to divide") + agōgos "leader," from agein "to lead" (from PIE root *ag- "to drive, draw out or forth, move").
In a historical sense from 1650s, "a leader of the masses in an ancient city or state, one who sways the people by oratory or persuasion." Often a term of disparagement since the time of its first use (in Athens, 5c. B.C.E.). Form perhaps influenced by French démagogue (mid-14c.).
Indeed, since the term demagogos explicitly denotes someone who leads or shepherds the demos, the eventual use of this word as the primary epithet for a political panderer represents a virtual reversal of its original meaning. The word demagogos in fact implies that the people need someone to lead them and that political power, at least in part, is exercised appropriately through this leadership. [Loren J. Samons II, "What's Wrong With Democracy," University of California Press, 2004]
A Latin word in a similar sense was plebicola "one who courts (literally 'cultivates') the common people," from plebs "the populace, the common people" + colere "to cultivate."