Much ingenuity has been spent on the etymology of this word by those who delight in recondite meanings, and believe that every word in Gaelic must be traced to a Gaelic origin. What Lhuyd says of radicals and primitives is equally applicable to other words. It is a very common error in etymology to endeavour to derive all the radical words of our Western European languages from the Latin or Greek; or indeed to derive the Primitives of any one language from any particular tongue. When we do this we seem to forget that all have been subject to alterations, and that the greater and more polite any nation is, the more subject they are (partly from improvement, and partly out of a luxurious wantonness) to remodel their language. Nearly all words connected with ecclesiastical affairs both in English and Gaelic have been imported from the Latin and Greek, undergoing only such changes as the difference of language requires. When or why the name of a Scandinavian deity, and not a Roman name, was adopted by the British and Irish churches to designate this or any other day is a different question. We must seek (and this is a rule lamentably neglected by Gaelic etymologists), the true explanation of words in any language that offers one that is probable and rational; otherwise we make “a useful art ridiculous,” and the etymologist degenerates into “a trifling conjecturer.”
The Latin name of this day is dies mercurii, which name was adopted in the Welsh, Cornish, and Armoric, but the Teutonic names are derived from the Scandinavian deity Odin or Woden, who was supposed to correspond to Mercury. This was the designation adopted in Gaelic, both Irish and Scottish. Like the French the Gaelic has no w, and represents that sound by g or c. Thus, gad, withe; gul, wail; cosd, waste; clòimh, wool; cnuimh, worm; curaidh, warrior, etc. Sometimes, as pointed out under Whitsuntide (caingis), the corresponding English sound is wh. So Woden’s-day, Wednesday, became Di-ceden.
The derivation ciad aoin’, first fast, is open to the objection that there was no fast on Wednesday in the Celtic or any other church, that the use of the word aoin’, to denote a fast, is secondary, and derived from Friday (di-haoine), the true fast day, and that the final syllable, being the essential one, would with such a derivation, be heavily accented, instead of falling away into a mere terminal syllable. The grave ia in Di-ciadain is accounted for by the o in Woden being long.
There was a malediction used to young women, “The disease of the woman be upon you, who put the first Wednesday comb in her head” (Galar na tè chuir a chiad chìr Chiadna na ceann). The disease was that she died childless.
Many would not begin sowing seed in spring, but on this day or Thursday. It was also counted a lucky day to begin ploughing upon.
A witch, in the island of Coll, being asked by a person, who had detected her in her unhallowed pranks, to visit a farm-house in shape of a hare, said, that as the day was Wednesday she could do nothing. Why her power was limited on this day does not appear.
Di’rdaoin, THURSDAY.
The Latin name, dies Iovis, has been similarly followed, with slight alteration, by the Cymric branch of the Celts; while the Gaelic names are taken from Thor, Tor, and in some dialects Thordan, the Scandinavian deity, son of Odin.
This is a lucky day for a calf or lamb to be born upon, for beginning the weaving of cloth, and on which the hair should be cut, as the rhymes testify:
(1) “Thursday the day of benign Colum-cill