Online Etymology Dictionary

calcaneus: from L. (os) calcaneum "bone of the heel," from calcem (nom. calx (1)) "heel."
calcareous: 1670s, from L. calcarius "of lime," from calx (gen. calcis) "lime, limestone" (see chalk).
calcify: 1785 (implied in calcified), from Fr. calcifier, from stem of L. calcem "lime" + -fy. Related: Calcification.
calcite: 1849, from Ger. Calcit, coined by Austrian mineralogist Wilhelm Karl von Hardinger (1795-1871), from L. calx (gen. calcis) "lime" + mineral suffix -ite (Ger. -it).
calcitrant: 1866, from L. calcitrantem "kicking" (see recalcitrant). Pedantic humor.
calcium: coined 1808 by Sir Humphry Davy from L. calx (gen. calcis) "limestone" (see chalk).
calculate: 1560s, "to compute, to estimate by mathematical means," from L. calculatus, pp. of calculare "to reckon, compute," from calculus (see calculus). Meaning "to plan, devise" is from 1650s. Replaced earlier calculen (mid-14c.), from O.Fr. calculer. Related: Calculable.
calculated: 1863, "devised beforehand," pp. adj. from calculate. Earlier, "suited, apt" (1722).
calculating: 1710, "carrying out calculations," prp. adj. from calculate. Meaning "shrewdly or selfishly seeking advantage" is attested from c.1810.
calculation: late 14c., from L.L. calculationem (nom. calculatio), from calculare "to reckon, compute," from L. calculus "reckoning, account," originally "pebble used in counting," dim. of calx (gen. calcis) "limestone" (see chalk).
calculator: late 14c., "mathematician, one who calculates," from L. calculator, from calculatus, pp. of calculare "to reckon, compute," from calculus (see calculus). Of mechanical adding machine contraptions, from 1784. Of electronic ones, from 1946.
"Electronic calculator uses 18,000 tubes to solve complex problems" ["Scientific American" headline, June 1946]
calculus: 1660s, from L. calculus "reckoning, account," originally "pebble used as a reckoning counter," dim. of calx (gen. calcis) "limestone" (see chalk). Modern mathematical sense is a shortening of differential calculus. Also used from 1732 to mean "concretion occurring accidentally in the animal body," such as dental plaque, kidney stones, etc.
Calcutta: city in eastern India, named for Hindu goddess Kali.
caldera: 1865, "cavity on the summit of a volcano," from Sp. caldera "cauldron, kettle," from L. caldarium, caldarius "pertaining to warming," from calidus "warm, hot" (see calorie).
caldron: spelling of cauldron prefered by other dictionary editors.
Caleb: masc. proper name, in the Bible, one of the 12 men sent by Moses to reconnoiter Canaan, from Heb. Kalebh, lit. "dog-like," from kelebh "dog."
Caledonia: Roman name of part of northern Britain, taken from the name of former inhabitants, of unknown origin, perhaps Celtic; since 18c, applied poetically to Scotland or the Scottish Highlands.
calendar: c.1200, "system of division of the year;" mid-14c. as "table showing divisions of the year;" from O.Fr. calendier "list, register," from L. calendarium "account book," from calendae/kalendae "calends" the first day of the Roman month -- when debts fell due and accounts were reckoned -- from calare "to announce solemnly, call out," as the priests did in proclaiming the new moon that marked the calends, from PIE base kele- "to call, shout" (see claim). Taken by the early Church for its register list of saints and their feast days. The -ar spelling in English is 17c. to differentiate it from the now obscure calender "cloth-presser" (see calender).
calender (v.): "to pass through a calender," a machine which smooths and presses paper, cloth, etc., 1510s, from Fr. calandre, the machine name, from M.L. calendra, so called from the shape of the machine used, from L. cylindrus, from Gk. kylindros "roll, cylinder" (see cylinder). The noun meaning "cloth-presser" is recorded from 1510s.
calf: O.E. cealf (Anglian cælf) "young cow," from W.Gmc. *kalbam (cf. M.Du. calf, O.N. kalfr, Ger. Kalb, Goth. kalbo), perhaps from PIE *gelb(h)-, from base *gel- "to swell," hence, "womb, fetus, young of an animal." Elliptical sense of "leather made from the skin of a calf" is from 1727. Used of icebergs that break off from glaciers from 1818. Calf of the leg (early 14c.) is from O.N. kalfi, source unknown; possibly from the same Germanic root.
caliber: 1560s, "degree of merit or importance," from M.Fr. calibre (14c.), perhaps ultimately from Arabic qalib "a mold, last," perhaps from Gk. kalopodion "a shoemaker's last," lit. "little wooden foot," from kalon "wood" + podos gen. of pous "foot" (see foot). Arabic also used the word in the sense "mold for casting bullets," which is the original literal meaning in English, though the earliest cited sense is a figurative one. Meaning "inside diameter of a gun barrel" is attested from 1580s.
calibrate: 1864, verb formed from caliber + -ate (2). Related: calibrated; calibrating; calibration.
calibre: British spelling of caliber (q.v.); for suffix, see -re.
calice: early form of chalice (q.v.).
caliche: sodium nitrate deposits in Chile and Peru, 1858, from Amer.Sp., from Sp. caliche "pebble in a brick," from L. calx "pebble."
calico: 1530s, kalyko, corruption of Calicut (modern Kozhikode), seaport on Malabar coast of India, where Europeans first obtained it. In 16c. it was second only to Goa among Indian commercial ports for European trade. Extended to animal colorings suggestive of printed calicos in 1807, originally of horses.
calid: 1590s, from L. calidus "warm," from PIE base *kele- "warm" (see calorie).
California: name of an imaginary realm in "Las sergas de Esplandián" ("Exploits of Espladán"), a romance by Sp. writer Garci Ordóñez de Montalvo, published in 1510, which was said to have been influential among Sp. explorers of the New World and may have led them to misidentify Baja California as this land and mistake it for an island. Where Montalvo got the name and what it means, if anything, is a mystery. Californian is attested from 1785. The element Californium (1950) was named in reference to University of California, where it was discovered.
caliginous: 1540s, from L. caliginosus "misty," from caliginem (nom. caligo) "mistiness, darkness, fog, gloom." Related: Caliginosity.
caligraphy: alt. spelling of calligraphy.
Caligula: cognomen of the third Roman emperor (12 C.E.-41 C.E.), born Gaius Caesar. The nickname is lit. "little boot," given when he joined his father on military campaigns when still a toddler, in full, child-sized military gear; dim. of caliga "heavy military shoe," which some related to calx "heel, tread," and others to a root meaning "to wrap, bind."
caliper: 1620s, short for calliper compass (1580s), a device used to measure caliber (q.v.). Related: Calipers.
caliph: late 14c., from O.Fr. caliphe (12c., also algalife), from M.L. califa, from Arabic khalifa "successor," originally Abu-Bakr, who succeeded Muhammad in the role of leader of the faithful after the prophet's death.
caliphate: "dominion of a caliph," 1610s, from caliph + -ate. Meaning "rank of a caliph" is recorded from 1753.
calisthenics: 1847 (calisthenic is from 1839), formed on model of Fr. callisthenie, from Gk. kallos "beauty" + sthenos "strength" + -ics. Originally, gymnastic exercises suitable for girls and meant to develop the figure and promote graceful movement. The proper Gk., if there was such a word in Gk., would have been *kallistheneia.
call (v.): O.E. ceallian "to call, shout," less common than clipian; replaced by related O.N. kalla "to cry loudly," from P.Gmc. *kallojanan (cf. Du. kallen "to talk," O.H.G. kallon "to call"), from PIE base *gal- "to call, scream, shriek, shout" (cf. Skt. garhati "bewail, criticize;" L. gallus "cock;" O.H.G. klaga, Ger. Klage "complaint, grievance, lament, accusation;" O.E. clacu "affront;" O.C.S. glasu "voice," glagolu "word;" Welsh galw "call"). As a noun, from early 14c. Meaning "to give a name to" is mid-13c. Coin-toss sense is from 1801. Meaning "to visit" (M.E.) was literally "to stand at the door and call;" noun sense of "a short formal visit" is from 1862. Telephone/telegraph sense is from 1889. To call out someone to fight (1823) corresponds to Fr. provoqueur. To call it a day is from 1834.
call girl: "prostitute who makes appointments by phone," c.1900, from call + girl.
caller: c.1500, "one who proclaims," from call. Meaning "one who announces step changes at a dance" is recorded from 1882; "one who places a telephone call," 1898. Meaning "a social visitor" is attested from 1786.
calligraphy: 1610s, from Gk. kaligraphia, from kallos "beauty" + graphein "to write" (see graph). Related: Calligraphic. The usual comb. form in Gk. was kalli- "beautiful, fine, happy, favorable;" kalo- was a later, rarer alternative form.
calling: "vocation," mid-13c., from prp. of call (v.). The sense traces to I Cor. vii:20.
calliope: 1858, "steam-whistle keyboard organ," in allusion to Calliope, ninth and chief muse, presiding over eloquence and epic poetry, from Gk. Kalliope, "lit. "beautiful-voiced," from kalli-, combining form of kallos "beauty" + opos (gen. of *ops) "voice," related to L. vox (see voice).
calliper: variant of caliper. Related: Callipers.
callipygian: "of, pertaining to, or having beautiful buttocks," 1800, from Gk. kallipygos, name of a statue of Aphrodite at Syracuse, from kalli-, combining form of kallos "beauty" + pyge "rump, buttocks." Sir Thomas Browne (1646) refers to "Callipygæ and women largely composed behinde."
Callisto: 2nd moon of Jupiter, in classical mythology a nymph, mother of Arcas by Zeus, turned to a bear by Hera, from Gk. kallistos, superl. of kalos "beautiful." Feminized as proper name Callista.
callithumpian: 1836, U.S. colloquial, probably a fanciful construction at one time designating a society of social reformers, then in reference to "noisy disturbers of elections and meetings," and most commonly "a band of discordant instruments."
callosal: "pertaining to the corpus callosum," from L. callosus + -al (1).
callous (adj.): c.1400, "hardened," in the physical sense, from L. callosus "thick-skinned," from callus, callum "hard skin" (see callus). The figurative sense of "unfeeling" appeared in English by 1670s.
callow: O.E. calu "bare, bald," prob. from W.Gmc. *kalwaz (cf. M.Du. calu, Du. kaal, O.H.G. kalo, Ger. Kahl), perhaps from L. or Celt. From young birds with no feathers, meaning extended to any young inexperienced thing or creature (1570s). Apparently not from L. calvus "bald."
callus (n.): "hardened skin," 1560s, from L. callus, variant of callum "hard skin," related to callere "be hard," and cognate with Skt. kalika "bud," O.Ir. calath "hard," O.C.S. kaliti "to cool, harden."
calm: late 14c., from O.Fr. calme, traditionally from O.It. calma, from L.L. cauma "heat of the mid-day sun" (in Italy, a time when everything rests and is still), from Gk. kauma "heat" (especially of the sun), from kaiein "to burn." Spelling influenced by L. calere "to be hot." Figurative application to social or mental conditions is 16c.