c. 1300, "off to one side;" mid-14c., "to or from the side;" late 14c., "away or apart from a normal direction or position, out of the way," from a- (1) "on" + side (n.). The noun sense of "words spoken so as to be (supposed) inaudible" is from 1727. Middle English had asidely "on the side, indirectly" (early 15c.) and asideward "sideways, horizontal" (late 14c.). It was used colloquially as a preposition from 1590s.
mid-13c., "a throw, an act of throwing," from cast (v.). In early use especially of dice, hence the figurative uses relating to fortune or fate. The meaning "that which is cast" is from mid-15c. The meaning "dash or shade of color" is from c. 1600.
The sense of "a throw" carried an idea of "the form the thing takes after it has been thrown," which led to widespread and varied meanings, such as "group of actors in a play" (1630s). OED finds 42 distinct noun meaning and 83 verbal ones, with many sub-definitions. Many of the figurative senses converged into a general meaning "sort, kind, style" (mid-17c.).
The meaning "model made from taking an impression of an object" is from c. 1500. A cast in the eye "slight squint" (early 14c.) preserves the older verbal sense of "warp, turn," via the notion of "permanent motion or turn." As "plaster molded around an injured or diseased part," by 1883.
c. 1200, "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), a word of uncertain origin.
The 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 In the sense of "to throw" it replaced Old English weorpan (see warp (v.)), and itself largely has been superseded by throw, though cast still is used of fishing lines (17c.)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" (accounts, etc.), late 15c. as "eject, vomit."
"something set aside," especially "commodities, agricultural products, etc., reserved by a government for some special purpose, originally military, 1943, from verbal phrase, probably in the sense of "separate out for a particular purpose" (1720); it originally meant "lay aside temporarily" (late 14c.); see set (v.) + aside (adv.). The verbal phrase also is attested as "dismiss from one's mind, leave out of the question" (c. 1400); "put on one side" (early 15c.); "discard or reject from use or service" (1570s).
1660s, cast iron, from iron (n.) + cast (adj.) "made by melting and being left to harden in a mold" (1530s), past-participle adjective from cast (v.) in its sense "to throw something (in a particular way)," c. 1300, especially "form metal into a shape by pouring it molten" (1510s). From 1690s as an adjective, "made of cast-iron;" figurative sense of "inflexible, unyielding" is from 1830.
mid-15c., "refusal, denial;" 1550s, "a castaway" (both now obsolete), from reject (v.) or obsolete reject (adj.). The sense of "thing cast aside as unsatisfactory" (1893) probably is a fresh extension. Hence "person considered low-quality and worthless" (1925, from use in the militaries in reference to men unsuitable for service).
"over the side of a ship," late Old English, from the phrase ofor bord, from over + bord "side of a ship" (see board (n.2)). To throw (something) overboard in the figurative sense of "cast aside, discard, reject" is from 1640s. Figurative sense of "excessively, beyond one's means" (especially in phrase go overboard) is attested by 1931 in Damon Runyon.
mid-14c., "an exile, a pariah, a person cast out or rejected," literally "that which is cast out," noun use of past participle of Middle English outcasten "to throw out or expel, reject," from out (adv.) + casten "to cast" (see cast (v.)). The adjective is attested from late 14c., "abject, socially despised." The verbal phrase cast out "discard, reject" is from c. 1200. In an Indian context, outcaste "one who has been expelled from his caste" is from 1876; see caste.