compound adjectival word-forming element, usually interchangeable with -ic but sometimes with specialized sense (such as historic/historical, politic/political), Middle English, from Late Latin -icalis, from Latin -icus + -alis (see -al (1)). Probably it was needed because the forms in -ic often took on a noun sense (for example physic). Forms in -ical tend to be attested earlier in English than their twins in -ic.

son of Daedalus in Greek mythology, from Latinized form of Greek Ikaros, a name of unknown origin, connected to Icaria and the Icarian Sea. He flew too high on artificial wings and so plunged to his death. Used allusively in English from 1580s.

also I.C.B.M., 1955, initialism (acronym) for Inter-Continental Ballistic Missile. IBM in the same sense is from 1954.

1855, from ice (n.) + age (n.). Perhaps translating German Eiszeit (1837). An earlier term in the same sense was glacial epoch (1841). Local scientific men had noticed from the late 18c. evidence that the Alpine glaciers once had been much larger; in the 1830s stray boulders, moraines, and polished bedrock in northern Europe (formerly interpreted as relics of catastrophic floods) began to be understood as revealing the former presence of a large ice cap there. When Agassiz, a convert to the theory, came to America in 1846 he found similar evidence in New England. The glacial theory and the notion that there had been several worldwide ice ages seems to have been generally accepted by the 1870s.

1774, "glacier humped like a hill;" 1820 as "detached piece of a glacier or ice pack at sea," partial loan-translation of Dutch ijsberg, literally "ice mountain," from ijs "ice" (see ice (n.)) + berg "mountain" (from PIE root *bhergh- (2) "high," with derivatives referring to hills and hill-forts.). Similar formation in Norwegian isberg, Danish isbjerg.

Earlier English terms were sea-hill (1690s), island of ice (1610s). Phrase tip of the iceberg in a figurative sense (in allusion to most of it being unseen underwater) first recorded 1962. Iceberg lettuce attested from 1893, apparently originally a trade name.

"obstructed by ice; frozen in; surrounded or hemmed in by ice, so as to prevent progress or approach," 1650s, from ice (n.) + bound (adj.1).

also icebox, 1839, "an ice chest," later "the small compartment in a refrigerator containing the ice," from ice (n.) + box (n.).

"a general or continuous permanent covering of a certain area of land, whether large or small, with snow or ice, especially in the arctic regions," 1859 in geology, from ice (n.) + an extended sense of cap (n.).

1941, originally a film title, from ice (n.) + a punning play on escapade.

1839, originally a wooden chest lined with zinc, from ice (n.) + chest (n.).