incohérent

Forms

incohérent (feminine incohérente, masculine plural incohérents, feminine plural incohérentes)^[1]

Etymology

It is formed from French in- + cohérent.^[2][3][4][1] The Grand Robert also suggests that it was formed after incohérence, or borrowed from English incoherent, recorded in English from the early 17th century;^[5] Littré derives it from Latin incohaerentem, an accusative form.^[6]

The base adjective is from Latin cohaerēns, the present participle of cohaereō (“to cling together”).^[3][7]

Earliest recorded meaning

Its first record is figurative: on 31 August 1751 Voltaire writes in a letter to the Duke of Richelieu of les incohérentes hardiesses de ce Lamétrie (“the incoherent audacities of this La Mettrie”), meaning lacking connection or logical sequence.^[2][8]

Semantic evolution

The physical sense “lacking cohesion” follows in 1779, in Horace-Bénédict de Saussure's Voyage dans les Alpes, of a crust like une poussière incohérente.^[2] The Académie (1798–1878) gave the example that the parts of water are incoherent;^[2] in geology couches incohérentes are layers without cohesion.^[6][2] These physical uses are now dated, while the abstract sense became the usual one.^[2][7]

Littré records métaphores incohérentes, metaphors joining incompatible images (1867).^[6][8] In physics, incohérent has been used in optics since 1858, of vibrations whose phase difference is not constant.^[7][4]

Timeline

• 1751 – Voltaire uses it figuratively in a letter.^[2][8]
• 1779 – Saussure uses it of a substance lacking cohesion.^[2]
• 1858 – First use in optics.^[7][4]
• 1867 – Littré records métaphores incohérentes.^[8]

Meanings

Adjective

1. incoherent: lacking connection, order or logic: Le malade tenait des propos incohérents.^[4][2]
2. Of conduct or a group: inconsistent, without unity: Sa politique est incohérente.^[4][8]
3. (physics) Of waves or vibrations: having a phase difference that is not constant.^[4][7]
4. (dated, physics, geology) Lacking cohesion between its parts: couches incohérentes.^[2][8][6]

Related words

• cohérent
• incohérence
• cohérence
• English incoherent

References

1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j Trésor de la langue française informatisé (2004), ATILF – CNRS & Université de Lorraine, atilf.fr/tlfi; electronic version of Imbs, Paul; Quemada, Bernard, eds. (1971–1994), Trésor de la langue française, Paris: CNRS / Gallimard
3. ^ a b Bloch, Oscar; Wartburg, Walther von (1989), Dictionnaire étymologique de la langue française, 8th ed., Paris: Presses universitaires de France
4. ^ a b c d e f Rey-Debove, Josette; Rey, Alain, eds. (2007), Le Petit Robert de la langue française, Paris: Le Robert
5. ^ Rey, Alain, ed. (2005), Le Grand Robert de la langue française, electronic version, Paris: Le Robert
6. ^ a b c d Littré, Émile (1873–1877), Dictionnaire de la langue française, 4 vols. and supplement, Paris: Hachette
7. ^ a b c d e Rey, Alain, ed. (1992), Dictionnaire historique de la langue française, Paris: Le Robert
8. ^ a b c d e f Guilbert, Louis; Lagane, René; Niobey, Georges, eds. (1971–1978; 1989), Grand Larousse de la langue française, Paris: Larousse