c. 1200, "to throw, throw violently, fling, hurl," from a Scandinavian source akin to Old Norse kasta "to throw" (cognate with Swedish kasta, Danish kaste, North Frisian kastin), of uncertain origin. Meaning "to form in a mold" is late 15c. In the sense of "to throw" it replaced Old English weorpan (see warp (v.)), and itself largely has been superseded now by throw, though cast still is used of fishing lines (17c.) and glances (13c.).
From c. 1300 as "emit, give out;" also "throw to the ground;" also "shed or throw off;" also "calculate, find by reckoning; chart (a course)." From late 14c. as "to calculate astrologically." From late 15c. as "bring forth abortively or prematurely." From 1711 as "distribute the parts (of a play) among the actors." Of votes from 1840, American English. To cast up is from 1530s as "compute, reckon," late 15c. as "eject, vomit."