The word means gibberish, meaningless talk, or nonsense. It appears in English first in 1653 in Sir Thomas Urquhart’s translation of the works of the French author François Rabelais: “A Galimatia of extravagant conceits.” Later writers have always put an “s” on the end, though it’s a singular:
Mrs. Tramore stared, as if at a language she had never heard, a farrago, a galimatias.
The Chaperon, by Henry James, a short story published in his collection The Real Thing and Other Tales in 1893.
It is in French that we must look for any enlightenment about its origins, since the word still exists in that language with the same sense. The number of theories about its origin is dauntingly large, however, strongly suggesting little firm information. We do know it’s first recorded in that language in 1580 in a work by Montaigne, but in the sense of an obscene song. For this reason, the most common view of its origin is that it’s from the low Latin ballematia, which had the same sense (old Italian had this last word, too, but for songs or melodies in a dance style).
Some writers point to an even older French word, gale, enjoyment, which joined up with a verb meaning to eat too much to create galimafrée for an unappetising dish (English gallimaufry, a jumble or confused medley, is from the same source). It has also been said galimatias was originally a disparaging slang term of the sixteenth century for the disputations prescribed for doctoral students at the University of Paris (Latin gallus, cockerel, plus the Greek ending -mathia, learning). Another writer has suggested a link with a Provençal word for an imaginary country. The experts now dismiss all of these out of hand.
The same word appears in Russian, presumably borrowed from French.