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MEANING

 

Borrowed from French, the noun éclair designates a small, oblong cake made of choux pastry, filled with cream, and typically topped with chocolate icing.

The literal meaning of this French noun is: lightning.

 

EARLY OCCURRENCES

 

I-: IN FRENCH

 

These are, in chronological order, the earliest occurrences of the French noun éclair—in the sense of a cake—that I have found:

1-: From L’Atelier de demoiselles ou l’apothicaire de Pontoise, by the French author Charles Paul de Kock (1793-1871), published in Galerie théâtrale : Choix de pièces nouvelles (Paris: Au Magasin central de pièces de théâtre anciennes et modernes, [1848]) [page 4, column 1]—this play premiered at the théâtre de la Gaîté, Paris, on 6^th February 1848:
—Context: A group of seamstresses are planning to go to a ball; one of them declares:

C’est Pétrin qui fournit la pâtisserie… Il y aura des éclairs, mesdemoiselles… vous savez, de ces petits gâteaux remplis de crême que ça vous crève dans la main… c’est tout ce qu’il y a de plus fashionable en petit four…
     translation:
It’s Pétrin who provides the pâtisserie… There will be éclairs, mesdemoiselles… you know, those little cakes so filled with cream that it bursts in your hand… it’s the absolute most fashionable as a petit four…

2-: From Les petits chiens de ces dames (Paris: Arnauld de Vresse, 1856), by the French author Henri de Kock (1819-1892), the son of Charles Paul de Kock [page 90]:

Madame charge de blancs de volaille l’assiette de Trilby. Il est fou des sucreries, des crêmes, des glaces. Tous les jours on lui sert sa petite charlotte russe, son nougat ou ses éclairs.
     translation:
Madam loads Trilby’s plate with poultry breasts. He is mad about sweets, creams, ice-creams. Every day he is served his little Russian charlotte, his nougat or his éclairs.

3-: From Le Pâtissier moderne ou traité élémentaire et pratique de la pâtisserie française au dix-neuvième siècle (Paris: Chez l’auteur, 1856), by Louis Bailleux [page 74]:

Éclairs.

[A detailed recipe, mentioning that éclairs can be filled with either coffee cream or chocolate cream, and topped with either coffee icing or chocolate icing.]

 

II-: IN ENGLISH

 

The earliest use in English of the noun éclair—in the sense of a cake—that I have found is from The Primpenny Family, by the U.S. author Fitz-Hugh Ludlow (1836-1870), published in Vanity Fair (New York City, New York, USA) of 2^nd February 1861 [Chapter 4; page 50, column 1]:

She departed to brew the punch.
In the course of fifteen minutes she returned, accompanied by Teague and a waiter, whereon stood a generous bowl of gilt china smothered in its own fragrant incense, goblets, and a plate of macaroons, éclairs and sponge cake.

 

ORIGIN: UNKNOWN

 

The question of why this cake is called éclair was posed in L’Intermédiaire des chercheurs et curieux (Paris: L’Intermédiaire des chercheurs et curieux) of 10^th February 1884 [Vol. XVII, page 66]:

Éclair, gâteau.—Quelle est l’origine de ce nom ? Vient-il comme le prétend Littré ¹, de la lumière causée par la foudre ou de la plante nommée éclaire, et dans ce cas doit-on appeler ce gâteau une éclaire ² ?
Gᴏᴍᴃᴏᴜꜱᴛ.
     translation:
Éclair, gâteau.—What is the origin of this name? Does it come, as Littré ¹ claims, from the light caused by lightning or from the plant called ‘éclaire’, and in that case must we call this cake ‘une éclaire’ ²?

¹ This refers to the French lexicographer Émile Littré (1801-1881), best known for Dictionnaire de la langue française (first edition: 1863-72; second edition: 1872-77). I have not, however, been able to ascertain if, or in which of his books, Littré claimed that éclair comes from the light caused by lightning or from the plant called éclaire.
² The French feminine noun éclaire is a name for the celandine, a plant of the buttercup family, having yellow flowers. Being feminine, éclaire is preceded by the indefinite article une; whereas the masculine noun éclair is preceded by the indefinite article un.

L’Intermédiaire des chercheurs et curieux published the following two answers:

1-: On 25^th February 1884 [page 122]:

Éclair, gâteau (XVII, 66).—Les éclairs que l’on vend en Belgique ont encore la forme en zigzags qui rappelle celle la foudre, d’où ils tirent probablement leur nom.
Vᴀʟᴅᴇꜱᴄʏɢɴᴇꜱ.
     translation:
Éclair, gâteau (XVII, 66).—The éclairs that are sold in Belgium still have the zigzag shape that recalls lightning, whence they probably take their name.

2-: On 10^th May 1884 [page 267]:

Éclair, gâteau (XVII, 66, 122).—A mon humble avis, il ne s’agit ni d’éclair ni d’éclaire. Le pâtissier, inventeur de ce gâteau l’a appelé éclair comme il lui aurait donné tout autre nom. La preuve, c’est qu’autrefois, à Toulouse, notre éclair parisien était appelé bâton de Jacob.
F. M.
     translation:
Éclair, gâteau (XVII, 66, 122).—In my humble opinion, it is neither about éclair nor éclaire. The pâtissier who invented this cake called it éclair as he would have given it any other name. Proof of this is that in the past, at Toulouse, our Parisian éclair was called Jacob’s staff.

The following text may support the theory that éclair is an arbitrary name—it is from Dictionnaire universel de cuisine : Encyclopédie illustrée d’hygiène alimentaire : Modification de l’homme par l’alimentation (Paris: Librairie-Imprimerie des Halles et de la Bourse de Commerce, [1891]), by the Swiss chef Joseph Favre (1849-1903) [Vol. 2, page 762, column 1]:

ÉCLAIR, s. m. (Pâtisserie). Autrefois appelé pain à la duchesse.—Petit gâteau en forme de bâton, fait de pâte à choux (Voir ce mot.), garni de crème et glacé.
     translation:
ÉCLAIR, s. m. (Pâtisserie). Formerly called bread à la duchess.—Small stick-shaped gâteau, made of choux pastry (See this word.), filled with cream and iced.

The following confirms that pain à la duchesse was one of the former names of the éclair—it is from Le Livre de pâtisserie (Paris: Librairie Hachette et C^ie, 1873), by the French chef and pâtissier Jules Gouffé (1807-1877) [page 288, s.v. pains à la duchesse au café]:

On a changé, depuis une vingtaine d’années, le nom de ces gâteaux ; on les désigne actuellement sous le nom d’éclairs.
     translation:
The name of those cakes was changed about twenty years ago; they are now called éclairs.