early 15c., populer, "public, commonly known," from Old French populaire and directly from Latin popularis "belonging to the people, general, common; devoted to or accepted by the people; democratic," from populus "people" (see people (n.)).
Meaning "of or pertaining to the people; depending on the people," especially the common people, is from 1540s. Meaning "suited to ordinary people, easily comprehended" is from 1570s in English; hence, of prices, "low, affordable to average persons" (1859).
The meaning "well-liked, admired by or enjoying the favor of the people" is attested from c. 1600. Of art, entertainment, etc., "favored by people generally" from 1819 (popular song). Related: Popularly. Popular Front "coalition of Communists, Socialists, and radicals" is from 1936, first in a French context.
Popular sovereignty, in U. S. hist., the theory that the right to decide whether slavery should exist in a territory rested with the people of that territory, and not with Congress. It was advocated especially by Democrats during the period 1847-61, and its leading champion was Douglas. It was often termed "squatter sovereignty," with which it was nearly identical. [Century Dictionary]