出典:Wiktionary
出典:『Wiktionary』 (2026/03/11 13:45 UTC 版)
Inherited from Proto-Italic *sinus, from Proto-Indo-European *sinos. Akin to Albanian gji (“breast, bosom”).
The mathematical sense “chord of an arc, sine” was introduced in the 12th century by Gherardo of Cremona as a semantic loan from Arabic جِيبَ (jība, “chord, sine”) (ultimately a loan from Sanskrit ज्या (jyā, “bowstring”)) by confusion with جَيْب (jayb, “bosom, fold in a garment”).
sinus m (genitive sinūs); fourth declension
Fourth-declension noun.
From Proto-Indo-European *sh₁ih₂sno-, deverbative of *seh₁y- (“to sift, strain”) (compare Ancient Greek ἠθέω (ēthéō), Lithuanian sijóti, Serbo-Croatian sȉjati).
sīnus m (genitive sīnī); second declension
Second-declension noun.
| singular | plural | |
|---|---|---|
| nominative | sīnus | sīnī |
| genitive | sīnī | sīnōrum |
| dative | sīnō | sīnīs |
| accusative | sīnum | sīnōs |
| ablative | sīnō | sīnīs |
| vocative | sīne | sīnī |
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名詞の変化形:
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