déflexion

Forms

déflexion f (plural déflexions)^[1]

Etymology

It is borrowed from Late Latin dēflexiō (“deviation, declension”), derived from dēflectō (“to turn aside”), the source of défléchir.^[2][3][4] It was first written deflection in the 16th century and taken up again in physics in the 18th.^[2][3]

Earliest recorded meaning

A 16th-century French translation of Aelian has deflection for a turning movement.^[2][3] The GLLF gives Godefroy's 16th-century sense as “going astray, error”.^[4]

Semantic evolution

The word was reborrowed as a term of physics in the mid-18th century, for a change in the path of light rays: the TLFi dates it to 1755 (Prévost), the Grand Robert and the Petit Robert to 1754, and the GLLF to the Académie's dictionary of 1762.^[2][3][5][4] It was later extended to beams of particles and to the flow of a fluid, and in aeronautics to the deflection of airflow behind a wing or a tail.^[2][4]

In medicine Larousse recorded it in 1878 for an extended position of a limb, and it now names the extended position of the fetus's head during birth.^[6][4][2] In late 19th-century linguistics it was an older name for apophonie (ablaut).^[4][6] Psychology and psychoanalysis use it for an unconscious turning away of attention.^[2][5]

Timeline

• 16th century – Deflection “turning movement” appears in a translation of Aelian.^[2]
• 1755 – Prévost uses it in physics.^[2]
• 1762 – The Académie records it of light.^[4]
• 1878 – Larousse records a surgical or medical sense.^[6][4]
• Late 19th century – It is used as an older term for ablaut.^[4]

Meanings

Noun

1. (physics) deflection of the path of a light beam, a beam of particles or the flow of a fluid.^[2][5]
2. (aviation) A change in direction of the airflow behind a wing or a tailplane.^[2][5]
3. (medicine) A position of extension, especially of the fetal head during childbirth, when it is normally flexed.^[2][5]
4. (psychology) A diversion or unconscious turning away of attention.^[2][5]
5. (linguistics, dated) Ablaut.^[4]

Related words

• défléchir
• déflecteur
• flexion
• Latin dēflectō

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m 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 c d Rey, Alain, ed. (2005), Le Grand Robert de la langue française, electronic version, Paris: Le Robert
4. ^ a b c d e f g h i j Guilbert, Louis; Lagane, René; Niobey, Georges, eds. (1971–1978; 1989), Grand Larousse de la langue française, Paris: Larousse
5. ^ a b c d e f Rey-Debove, Josette; Rey, Alain, eds. (2007), Le Petit Robert de la langue française, Paris: Le Robert
6. ^ a b c Quemada, Bernard, ed. (1959–2006), Datations et documents lexicographiques (Base historique du vocabulaire français, BHVF), Paris: Klincksieck / CNRS / Champion; ATILF