Etymology can take some peculiar turns as a word criss-crosses different cultures. For the latest installment of Slate's Lexicon Valley podcast, I take the hosts along on the journey of the word cockamamie, which might seem stranger than fiction.

Improbably enough, that journey starts in Paris in 1862. News was emanating from the city about a brand-new fad for ornamentation by means of "transfer pictures," going by the name decalcomanie:

The great rage among the ladies of Paris just at present is decalcomanie.
Memphis Daily Appeal, July 5, 1862, p. 1

By the following year, Anglicized as decalcomania, the fad had spread to Britain and Ireland, as described in this advertisement:

Decalcomania is the art of ornamenting, instantaneously, Furniture, Wood, Wax-Lights, Silks, Linen, Calico, China, and every description of Plaster of Paris, Porcelain, Alabaster, Ivory, Paper, Paper Hangings, Tea Trays, Oilcloth, and all kinds of Fancy Goods of ceramic substances, by means of designs on paper, and Varnishes expressly prepared.
Belfast News-Letter, Feb. 7, 1863, p. 2

And in another year, the ornamental fad had crossed the Atlantic, even in the midst of the Civil War:

DECALCOMANIE. This new fancy work bids fair to become as popular here as it already is in France and England... A friend called on us the other evening, and in the course of conversation drew from his pocket a small bottle of varnish and some beautiful little paintings, flower groups and other dainty designs, and asking for some plain china cup or vase that we would like ornamented, proceeded to astonish us. A small paint brush, dipped into the varnish, was passed carefully over the painting, which was then laid, varnish side downwards, upon the flat top of a semitransparent white glass cup. Then with an old soft linen handkerchief, slightly wet, the paper was moistened and deftly drawn away, leaving the bright flower group as firmly set apparently as if it always had been there—the whole operation not occupying five minutes.
The Lady's Friend, May 1864

Originally, decalcomanie referred to the fad itself: it was a "mania" (manie) for transferring pictures by means of a process called decalquer, literally "tracing (as with tracing paper)." Decalquer ultimately derives from Latin calx "heel" and calcare "to tread," with the French verb calquer coming to refer to the act of pressing down, as you would when tracing something. It also lives on in the word calque, another term for what linguists call "loan-translation," in which a word or phrase is translated (or "traced") from one language in a literal fashion, as in Nietzsche's Übermensch becoming Shaw's Superman.

The name for the fad then became the name for the process, and in English, the transfer pictures used in the ornamentation could themselves be called decalcomanias. That's a mouthful, and over time, beginning in American trade journals, decalcomania got shortened to the two-syllable decal:

Some of their decorations were exceedingly good, yet repeat orders were often declined because they had stopped using that special decal.
Glass and Pottery World, Mar. 1905, p. 21

The word decal wouldn't really become popular until after World War II, by which time the "transfer pictures" it described had changed from old-fashioned paper strips to bits of sticky plastic affixed to car windows, model airplanes, and the like.

But in the meantime, another shortening of decalcomania developed on the streets of New York, where the transfer pictures became popular in the form of cheap temporary tattoos that children would put on their skin. Decalcomania lost its first syllable, and the remaining calcomania then ended up getting pronounced (and spelled) as cockamanie or, you guessed it, cockamamie.

Here is how the humorist Arthur Kober, in a 1931 story for The New Yorker, described the cockamanies of his Bronx childhood (he was born in eastern Europe in 1900 and emigrated to New York with his family four years later):

Then there were "cockamanies," painted strips of paper you applied to your wrist, and rubbed with spit until the image was transferred to your hand. It was an exciting form of tattooing and there was quite a demand for them.
—"Mrs. Gittleson," The New Yorker, Oct. 24, 1931, p. 73

Kober grew up among Yiddish speakers, and Yiddish seems to have played a role in reshaping the old word decalcomania. Leo Rosten, in The Joys of Yiddish (1968), wrote, "I am informed by veterans of the Lower East Side that decalcomania pictures were called 'cockamamies' because no one knew how to spell 'decalcomania.'"

There were many variant spellings of the word that the children were using. Another New Yorker item from the '30s spelled it as kakamanies:

The new relief-tax stamps which must appear on all packages of cigarettes sold in New York City after April 30th represent an interesting revival of decalcomania — "transfer pictures" in grade-school parlance, or "kakamanies."
The New Yorker, Apr. 23, 1938, p. 14

However they were spelled, these temporary tattoos gave rise to a new meaning of cockamamie, originally a noun referring to something of little value or even fraudulent. The actress Shelly Winters, raised in Brooklyn, self-deprecatingly likened most of her movies to cockamamies, and The New York Times explained what she meant:

"Most of the pictures I made in the seven years I was a Hollywood star," Miss Winters said, "were like cockamamies." (This word, translated from the Brooklynese, is the authorized pronunciation of decalcomania. Anyone there who calls a cockamamie a decalcomania is stared at.)
The New York Times, Apr 29, 1956

The word could also be used for an odd or frivolous person, as in this exchange in Sidney Kingsley's 1935 play Dead End, a dialect-heavy portrait of tough kids growing up in New York slums that would serve as the basis of "The Dead End Kids" and "The Bowery Boys":

Angel: Yuh see duh pitchuh uv 'is broad inna papuhs? Deedy Cook aw sump'm...
T.B.: Boy, some nice nooky, huh?
Spit: Boy, she's got some contrac's now! I heah she's gonna do a bubble dance in a boilesque, I t'ink.
Angel: Yeah. My fadduh took one look at huh pitchuh. So 'ee said 'ee'd let 'em shoot 'im too, fuh half an hour wid' a fancy floozy like dat. So my mudduh gits mad. So she sez dey wouldn' haf tuh shoot cha. Haf an hour wid' 'at cockamamee, yuh'd be dead!
—Sidney Kingsley, Dead End, 1935

The first known use of cockamamie as an adjective comes from the 1942 film Woman of the Year, the first to pair Spencer Tracy and Katherine Hepburn. (One red herring is a 1921 blues song called "Kiss Your Pretty Baby Nice" sung by Ethel Waters. Some have transcribed Waters as singing about a man's "cockamamy style," but if you listen closely, she's actually singing "fascinating style.")

In Woman of the Year, bar owner Pinkie Peters (played by the great character actor William Bendix) makes sure that the bartender serves the good stuff when Tracy's character, a sportswriter, brings in Hepburn's character, a sophisticated foreign affairs columnist: "Don't give 'em none of that cockamamie bar stock, you hear?"

In that usage, cockamamie still means something like "low-quality" or "knock-off," but the adjective got extended to all manner of nutty, hare-brained or untrustworthy things. At first glance, even this etymology might appear cockamamie, but the historical record supports all the crazy twists and turns.