Online Etymology Dictionary

calabash (n.): 1590s, "dried, hollowed gourd used as a drinking cup," from Spanish calabaza, possibly from Arabic qar'a yabisa "dry gourd," from Persian kharabuz, used of various large melons; or from a pre-Roman Iberian *calapaccia.
calaboose (n.): "prison," 1792, American English, from Louisiana French calabouse, from Spanish calabozo "dungeon," probably from Vulgar Latin *calafodium, from pre-Roman *cala "protected place, den" + Latin fodere "to dig" (see fossil).
Calais: city on the French coast of the English Channel, from Gaulish Caleti, the name of a Celtic people who once lived along the shore there.
calamari (n.): 1560s, from Italian calamari, from Latin calamarius, literally "pertaining to a pen," from calamus "a writing pen," literally "reed" (see shawm). So called from the cuttlefish's pen-like internal shell and perhaps also from its being full of ink.
calamine (n.): zinc carbonate; zinc silicate, 1590s, from French calamine, from Old French calemine, chalemine (13c.), from Medieval Latin calamina, corrupted by alchemists from Latin cadmia "zinc ore," from Greek kadmeia (see cadmium). Or possibly the Medieval Latin word is from Latin calamus "reed," in reference to the mineral's shape.
calamitous (adj.): 1540s, from French calamiteux (16c.), from Latin calamitosus "causing loss, destructive," from calamitas (see calamity). Related: Calamitously; calamitousness.
calamity (n.): early 15c., from Middle French calamite (14c.), from Latin calamitatem (nominative calamitas) "damage, loss, failure; disaster, misfortune, adversity," origin obscure. Early etymologists associated it with calamus "straw" (see shawm); but it is perhaps from a lost root preserved in incolumis "uninjured," from PIE *kle-mo-, from base *kel- (1) "to strike, cut" (see holt).
calcaneus (n.): from Latin (os) calcaneum "bone of the heel," from calcem (nominative calx (1)) "heel," a word of uncertain origin, perhaps from Etruscan. De Vaan lists as possible cognates Old Prussian culczi "hip," Lithuanian kulkšnis "ankle-(bone)" Bulgarian kalka "hip, thigh."
calcareous (adj.): also calcarious, 1670s, from Latin calcarius "of lime," from calx (genitive calcis) "lime, limestone" (see chalk (n.)).
calcify (v.): 1785 (implied in calcified), from French calcifier, from stem of Latin calcem "lime" (see chalk (n.)) + -fy. Related: Calcifying; calcification.
calcite (n.): crystalling calcium carbonate, 1849, from German Calcit, coined by Austrian mineralogist Wilhelm Karl von Hardinger (1795-1871) from Latin calx (genitive calcis) "lime" (see chalk (n.)) + mineral suffix -ite (2) (German -it).
calcitrant (adj.): 1866, as if from Latin calcitrantem (nominative calcitrans) "kicking" (see recalcitrant). Pedantic humor; probably a back-formation.
calcium (n.): coined 1808 by English chemist Sir Humphrey Davy (1778-1829), who first succeeded in isolating it, from Latin calx (genitive calcis) "limestone" (see chalk (n.)) + metallic element ending -ium.
calculate (v.): 1560s, "to compute, to estimate by mathematical means," from Latin calculatus, past participle of calculare "to reckon, compute," from calculus (see calculus). Meaning "to plan, devise" is from 1650s. Replaced earlier calculen (mid-14c.), from Old French calculer. Related: Calculable.
calculated (adj.): 1796, "devised beforehand," past participle adjective from calculate (v.). Earlier, "suited, apt" (1722).
calculating (adj.): 1710, "carrying out calculations," present participle adjective from calculate (v.). Meaning "shrewdly or selfishly seeking advantage" is attested from c. 1810.
calculation (n.): late 14c., from Late Latin calculationem (nominative calculatio), noun of action from past participle stem of calculare "to reckon, compute," from Latin calculus "reckoning, account," originally "pebble used in counting," diminutive of calx (genitive calcis) "limestone" (see chalk (n.)).
calculator (n.): late 14c., "mathematician, one who calculates," from Latin calculator, from calculatus, past participle 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 (n.): 1660s, from Latin calculus "reckoning, account," originally "pebble used as a reckoning counter," diminutive of calx (genitive calcis) "limestone" (see chalk (n.)). Modern mathematical sense is a shortening of differential calculus. Also used from 1732 to mean kidney stones, etc., then generally for "concretion occurring accidentally in the animal body," such as dental plaque. Related: Calculous (adj.).
Calcutta: city in eastern India, named for Hindu goddess Kali.
caldera (n.): "cavity on the summit of a volcano," 1865, from Spanish caldera "cauldron, kettle," from Latin caldarium, caldarius "pertaining to warming," from calidus "warm, hot" (see calorie).
caldron (n.): spelling of cauldron preferred by other dictionary editors.
Caleb: masc. proper name, in the Bible, one of the 12 men sent by Moses to reconnoiter Canaan, from Hebrew Kalebh, literally "dog-like," from kelebh "dog."
Caledonia: Roman name of part of northern Britain, taken from the name of former inhabitants, which is of unknown origin, perhaps Celtic; since 18c, applied poetically to Scotland or the Scottish Highlands. Related: Caledonian.
calendar (n.): c. 1200, "system of division of the year;" mid-14c. as "table showing divisions of the year;" from Old French calendier "list, register," from Latin calendarium "account book," from calendae/kalendae "calends" the first day of the Roman month -- when debts fell due and accounts were reckoned.

This is from calare "to announce solemnly, call out," as the priests did in proclaiming the new moon that marked the calends, from PIE root kele- (2) "to call, shout" (see claim (v.)). In Rome, new moons were not calculated mathematically but rather observed by the priests from the Capitol; when they saw it, they would "declare" the number of days till the nones (five or seven, depending on the month). The word was taken by the early Church for its register list of saints and their feast days.

Sometimes used in a general sense, "to insert between others" (1824). The -ar spelling in English is 17c. to differentiate it from the now obscure calender "cloth-presser."
calender (v.): "to pass through a calender," a machine which smooths and presses paper, cloth, etc., 1510s, from Middle French calandre, the machine name, from Medieval Latin calendra (see calender (n.)).
calender (n.): "machine which smooths and presses paper, cloth, etc.," 1510s (late 13c. in surnames of persons who use such a machine), 1510s, from Old French calandreur, from Medieval Latin calendra "cloth-pressing machine," so called from the shape of the machine used, from Latin cylindrus, from Greek kylindros "roll, cylinder" (see cylinder).
calf (n.1): "young cow," Old English cealf (Anglian cælf) "young cow," from Proto-Germanic *kalbam (source also of Middle Dutch calf, Old Norse kalfr, German Kalb, Gothic kalbo), perhaps from PIE *gelb(h)-, from root *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 (n.2): fleshy part of the lower leg, early 14c., from Old Norse kalfi, source unknown; possibly from the same Germanic root as calf (n.1).
caliber (n.): 1560s, "degree of merit or importance," a figurative use from Middle French calibre (late 15c.), apparently ultimately from Arabic qalib "a mold for casting." Arabic also used the word in the sense "mold for casting bullets," which is the oldest literal meaning in English. Meaning "inside diameter of a gun barrel" is attested from 1580s. Barnhart remarks that Spanish calibre, Italian calibro "appear too late to act as intermediate forms" between the Arabic word and the French.
calibrate (v.): 1839, verb formed from caliber + -ate (2). Related: calibrated; calibrating.
calibration (n.): 1854, noun of action from calibrate.
calibre (n.): chiefly British English spelling of caliber (q.v.); for spelling, see -re.
calice (n.): early form of chalice (q.v.).
caliche (n.): sodium nitrate deposits in Chile and Peru, 1858, from American Spanish, from Spanish caliche "pebble in a brick," from Latin calx "pebble" (see chalk (n.)).
calico (n.): 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 (adj.): 1590s, from Latin calidus "warm," from PIE root *kele- (1) "warm" (see calorie).
California: name of an imaginary realm in "Las sergas de Esplandián" ("Exploits of Espladán"), a romance by Spanish writer Garci Ordóñez de Montalvo, published in 1510. It was a sequel to his "Amadis de Gaula," and was said to have been influential among Spanish explorers of the New World. It could have led them to misidentify Baja California as this mythical land and to mistake it for an island. The Amadis tales are the Iberian equivalent of the Arthurian romances; they are older than 1510 (traces of them have been found mid-14c.) and were wildly popular. That conquistadors and sailors would have known the story in all its imaginative detail is hardly surprising.
Amadis de Gaula ... set a fashion: all later Spanish writers of books of chivalry adopted the machinery of Amadis de Gaula. Later knights were not less brave (they could not be braver than) Amadis; heroines were not less lovely (they could not be lovelier) than Oriana; there was nothing for it but to make the dragons more appalling, the giants larger, the wizards craftier, the magic castles more inaccessible, the enchanted lakes deeper. Subsequent books of chivalry are simple variants of the types in Amadis de Gaula: Cervantes made his barber describe it as 'the best of all books of this kind.' This verdict is essentially just. Amadis de Gaula was read everywhere, especially in the French version of Herberay des Essarts. It was done into Hebrew during the sixteenth century, and attracted readers as different as St Ignatius of Loyola and Henry of Navarre. Its vogue perhaps somewhat exceeded its merit, but its merits are not inconsiderable. [James Fitzmaurice-Kelly, "Spanish Literature," 1922 edition]
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 (adj.): 1540s, from Latin caliginosus "misty," from caliginem (nominative caligo) "mistiness, darkness, fog, gloom." Related: Caliginosity.
caligraphy (n.): alternative spelling of calligraphy.
Caligula: cognomen of the third Roman emperor (12 C.E.-41 C.E.), born Gaius Caesar. The nickname is Latin, literally "little boot," given when he joined his father on military campaigns when still a toddler, in full, child-sized military gear; diminutive of caliga "heavy military shoe," which is of unknown origin.
caliper (n.): 1620s, short for calliper compass (1580s), a device used to measure caliber (q.v.). Related: Calipers.
caliph (n.): late 14c., from Old French caliphe (12c., also algalife), from Medieval Latin 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 (n.): "dominion of a caliph," 1610s, from caliph + -ate (1). Meaning "rank of a caliph" is recorded from 1753.
calisthenics (n.): 1847 (calisthenic (adj.) is from 1839), formed on model of French callisthenie, from Latinized comb. form of Greek kallos "beauty" (see Callisto) + sthenos "strength" + -ics. Originally, gymnastic exercises suitable for girls and meant to develop the figure and promote graceful movement. The proper Greek, if there was such a word in Greek, would have been *kallistheneia.
call (v.): Old English ceallian "to call, shout," less common than clipian; replaced by related Old Norse kalla "to cry loudly," from Proto-Germanic *kall- (source also of Dutch kallen "to talk," Old High German kallon "to call"), from PIE root *gal- (2) "to call, scream, shriek, shout" (source also of Sanskrit garhati "bewail, criticize;" Latin gallus "cock;" Old High German klaga, German Klage "complaint, grievance, lament, accusation;" Old English clacu "affront;" Old Church Slavonic glasu "voice," glagolu "word;" Welsh galw "call"). Related: Called; calling.

Meaning "to give a name to" is mid-13c. Coin-toss sense is from 1801. Meaning "to visit" (Middle English) was literally "to stand at the door and call." Telephone/telegraph sense is from 1889. To call out someone to fight (1823) corresponds to French provoquer. To call it a day is from 1834.
call (n.): early 14c., from call (v.). Sense of "a short formal visit" is from 1862.
call girl (n.): "prostitute who makes appointments by phone," c. 1900, from call + girl.
caller (n.): c. 1500, "one who proclaims," agent noun from call (v.). 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 (n.): 1610s, from Greek kaligraphia, from kallos "beauty" (see Callisto) + graphein "to write" (see -graphy). Related: Calligraphic. The usual comb. form in Greek was kalli- "beautiful, fine, happy, favorable;" kalo- was a later, rarer alternative form.