The word comes from the French éclair, meaning 'flash of lightning', so named because it is eaten quickly (in a flash);[5] however some believe that the name is due to the glistening of the frosting resembling lightning.[6]
History
The éclair originated during the 19th century in Lyon,[7] France where it was called pain à la Duchesse[8] ('Duchess-style bread') or petite duchesse ('little duchess') until 1850.[9] The word is first attested both in English and in French in the 1860s.[10][11]
↑(Gouffé 1873, p.288)On a changé, depuis une vingtaine d'années, le nom de ces gâteaux [pains à la duchesse]: on les désigne actuellement sous le nom d'éclairs.