équatorial

Forms

équatorial (feminine équatoriale, masculine plural équatoriaux, feminine plural équatoriales)^[1]

Etymology

It is a learned formation from Medieval Latin aequātor (“equator”) with the suffix -ial,^[2][3][4] the Latin noun behind équateur.^[2][5] Wiktionary takes it from aequātōriālis.^[1] The Medieval Latin noun is from aequō (“to make equal”).^[5]

Earliest recorded meaning

It is first found in Buffon in 1778, meaning “relating to the equator”.^[4][6][3]

Semantic evolution

The adjective applies to whatever relates to the equator, and by analogy, like équateur, is used in several fields.^[3] It describes the regions near the Earth's equator, their climate and vegetation, and in astronomy the celestial equator.^[6][7]

The lunette équatoriale (1784), which measures the right ascension and declination of a star, gave the noun équatorial for that instrument;^[3] the TLFi dates the noun itself to 1784, Rey to 1858 and the GLLF to Littré (1864).^[2][3][6]

Timeline

• 1778 – Buffon uses the adjective.^[4][6][3]
• 1784 – The Encyclopédie méthodique has the noun for an astronomical instrument.^[2]
• 1858 – Rey's date for the noun équatorial.^[3]
• 1864 – Littré records the astronomical senses.^[6]

Meanings

Adjective

1. Relating to the Earth's equator or to the regions near it: les régions équatoriales.^[7][6]
2. Climat équatorial: the climate of the regions on either side of the equator, hot all year with heavy, regular rain.^[6][7]
3. (astronomy) Relating to the celestial equator: coordonnées équatoriales, a star's right ascension and declination.^[7][6]

Noun

1. (astronomy) An instrument like a theodolite that measures a star's right ascension and declination.^[7][8][3]

Related words

• équateur
• Medieval Latin aequātor

References

1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d 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 e f g h Rey, Alain, ed. (1992), Dictionnaire historique de la langue française, Paris: Le Robert
4. ^ a b c Rey, Alain, ed. (2005), Le Grand Robert de la langue française, electronic version, Paris: Le Robert
5. ^ a b Bloch, Oscar; Wartburg, Walther von (1989), Dictionnaire étymologique de la langue française, 8th ed., Paris: Presses universitaires de France
6. ^ a b c d e f g h Guilbert, Louis; Lagane, René; Niobey, Georges, eds. (1971–1978; 1989), Grand Larousse de la langue française, Paris: Larousse
7. ^ a b c d e Rey-Debove, Josette; Rey, Alain, eds. (2007), Le Petit Robert de la langue française, Paris: Le Robert
8. ^ Littré, Émile (1873–1877), Dictionnaire de la langue française, 4 vols. and supplement, Paris: Hachette