plagio-

also *plāk-, Proto-Indo-European root meaning "to be flat;" extension of root *pele- (2) "flat; to spread."

It forms all or part of: flag (n.2) "flat stone for paving;" flagstone; flake (n.) "thin flat piece,; flaw; floe; fluke (n.3) "flatfish;" placenta; plagal; plagiarism; plagio-; planchet; plank.

It is the hypothetical source of/evidence for its existence is provided by: Greek plakoeis "flat," plax "level surface, anything flat;" Lettish plakt "to become flat;" Old Norse flaga "layer of earth," Norwegian flag "open sea," Old English floh "piece of stone, fragment," Old High German fluoh "cliff."

"triclinic feldspar," 1868, coined in German 1847 by German mineralogist Johann Friedrich August Breithaupt (1791-1873) from plagio- "slanting" + Greek klasis "a fracture," from stem of klan "to break" (see clastic). So called because the two prominent cleavage directions are oblique to each other. Related: Plagioclastic.