What is the X in X-mas?
c.1300, "a throwing; late 14c., "a metal casting, a product of a cast;" verbal noun from cast (v.). Theatrical sense is from 1814. Casting couch in the naughty-Hollywood sense is from 1948.
c.1200, from a Scandinavian source akin to Old Norse kasta "to throw" (cf. Swedish kasta, Danish kaste, North Frisian kastin), of uncertain origin. Meaning "to form in a mold" is late 15c. In the sense of "warp, turn" it replaced Old English weorpan (see warp (v.)), and itself largely has been superseded now by throw, though cast still is used of fishing lines and glances.
mid-13c., "a throw, an act of throwing," from cast (v.). In early use especially of dice, hence figurative uses relating to fortune or fate. Meaning "that which is cast" is from c.1550s. 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 in a general meaning "sort, kind, style" (mid-17c.). A cast in the eye (early 14c.) preserves the older verbal sense of "warp, turn."
An object formed by the solidification of molten liquid poured into an impression or mold, as in a dental cast of the maxillary or mandibular arch.
A rigid dressing, usually made of gauze and plaster of Paris, used to immobilize an injured, fractured, or dislocated body part, as in a fracture or dislocation. Also called plaster cast.
A mass of fibrous material, coagulated protein, or exudate that has taken the form of the cavity in which it has been molded, such as the bronchial, renal, intestinal, or vaginal cavity, and that is found histologically as well as in urine or sputum samples.