sīdus

sīdus uit.-lat.

Tentatively thought to derive from a Proto-Italic *sīþos (“mark, target”), with a putative semantic shift (from hunters' jargon) from "target" > "star". Further origin unclear, with multiple theories proposed:

• Some derive this from Proto-Indo-European *sweyd- (“sweat”), whence Latin sūdor, Ancient Greek ἱδρώς (hidrṓs), English sweat; however there are phonetic problems, most notably the initial /s/in Greek instead of expected */h/.
• Rix, connecting the word to Ancient Greek ῑ̓θῠ́ς (īthús, “straight, just”) and Sanskrit साध् (sādh, “to go straight to a goal”), derives the terms from a Proto-Indo-European *seHdʰ- (“to achieve a goal”), and the Latin from a reduplicative form *si-sHdʰ-u- > *sisdʰu- > *sizdu- > *sīdu-. This is semantically tenuous.
• Compare Ancient Greek σίδηρος (sídēros, “iron”). This is semantically unconvincing.
• Possibly borrowed from a substrate.
• Perhaps from a Proto-Indo-European *sh₂i-dʰh₁-o- (“binding”), from *sh₂ey- (“to bind, tie, fasten”), whence saeculum (“age, race, generation”). De Vaan tentatively prefers this derivation.

Pronunciation

• (Classical Latin) IPA^(key): /ˈsiː.dus/, [ˈs̠iːd̪ʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈsi.dus/, [ˈsiːd̪us]

Noun

sīdus n (genitive sīderis); third declension

1. group of stars, constellation, asterism [ quotations ▼]
2. a star [ synonyms ▲]

   Synonyms: astēr, astrum, stēlla

3. (poetic) the night sky
4. (figuratively) a season (of the year)

Declension

Third-declension noun (neuter, imparisyllabic non-i-stem).

Case	Singular	Plural
Nominative	sīdus	sīdera
Genitive	sīderis	sīderum
Dative	sīderī	sīderibus
Accusative	sīdus	sīdera
Ablative	sīdere	sīderibus
Vocative	sīdus	sīdera

Derived terms

• cōnsīderō
• dēsīderō
• sīderālis
• sīdereus
• sīderor

See also

• stella
• astrum