a modern book-form to represent Old English run, rune "secret, mystery, dark mysterious statement, (secret) council," also "a runic letter" (runstæf), from Proto-Germanic *runo (source also of Old Norse run "a secret, magic sign, runic character," Old High German runa "a secret conversation, whisper," Gothic runa), from PIE *ru-no-, source of technical terms of magic in Germanic and Celtic (source also of Gaelic run "a secret, mystery, craft, deceit, purpose, intention, desire," Welsh rhin "a secret, charm, virtue"). Also see Runnymede.
The word entered Middle English as roun and by normal evolution would have become Modern English *rown, but it died out mid-15c. when the use of runes did. The modern usage is from late 17c., from German philologists who had reintroduced the word in their writings from a Scandinavian source (such as Danish rune, from Old Norse run).
The presumption often is that the magical sense was the original one in the word and the use of runes as letters was secondary to ancient Germanic peoples, but this is questioned by some linguists. The runic alphabet itself is believed to have developed by 2c. C.E. from contact with Greek writing, with the letters modified to be more easily cut into wood or stone. Related: Runed; runecraft.
"pertaining to or consisting of runes," 1660s, from Modern Latin runicus, from Old Norse run (see rune). It also was sometimes used as a general word for the art and decorative styles of early Northern Europe.
Old English is "ice, piece of ice" (also the name of the Anglo-Saxon rune for -i-), from Proto-Germanic *is- "ice" (source also of Old Norse iss, Old Frisian is, Dutch ijs, German Eis), of uncertain origin; possible relatives are Avestan aexa- "frost, ice," isu- "frosty, icy;" Afghan asai "frost." Slang meaning "diamonds" is attested from 1906.
Modern spelling begins to appear 15c. and makes the word look French. On ice "kept out of the way until wanted" is from 1890. Thin ice in the figurative sense is from 1884. To break the ice "to make the first opening to any attempt" is from 1580s, metaphoric of making passages for boats by breaking up river ice though in modern use it usually has implications of "cold reserve." Ice-fishing is from 1869; ice-scraper is from 1789 in cookery.
A sound found chiefly in words of Old English, Old Norse or Greek origin, unpronounceable by Normans and many other Europeans. In Greek, the sound corresponds etymologically to Sanskrit -dh- and English -d-; and it was represented graphically by -TH- and at first pronounced as a true aspirate (as still in English outhouse, shithead, etc.).
But by 2c. B.C.E. the Greek letter theta was in universal use and had the modern "-th-" sound. Latin had neither the letter nor the sound, however, and the Romans represented Greek theta by -TH-, which they generally pronounced, at least in Late Latin, as simple "-t-" (passed down to Romanic languages, as in Spanish termal "thermal," teoria "theory," teatro "theater").
In Germanic languages it represents PIE *-t- and was common at the start of words or after stressed vowels. To represent it, Old English and Old Norse used the characters ð "eth" (a modified form of -d-) and þ "thorn," which originally was a rune. Old English, unlike Old Norse, seems never to have standardized which of the two versions of the sound ("hard" and "soft") was represented by which of the two letters.
The digraph -th- sometimes appears in early Old English, on the Roman model, and it returned in Middle English with the French scribes, driving out eth by c. 1250, but thorn persisted, especially in demonstratives (þat, þe, þis, etc.), even as other words were being spelled with -th-. The advent of printing dealt its death-blow, however, as types were imported from continental founders, who had no thorn. For a time y was used in its place (especially in Scotland), because it had a similar shape, hence ye for the in historical tourist trap Ye Olde _______ Shoppe (it never was pronounced "ye," only spelled that way).
The awareness that some Latin words in t- were from Greek th- encouraged over-correction in English and created unetymological forms such as Thames and author, while some words borrowed from Romanic languages preserve, on the Roman model, the Greek -th- spelling but the simple Latin "t" pronunciation (as in Thomas and thyme).