Appendix:Latin fifth declension

Description
Latin nouns of the fifth declension end in -ēs in the nominative singular, with a genitive in -ēī (after -i-) or in -ĕī (after consonant), and have an invariable stem. Other than, , and , fifth-declension nouns generally end more specifically in -iēs. Some nouns show variation between fifth-declension forms in -iēs and first-declension forms in -ia.

All fifth declension nouns are feminine except (which was originally masculine, but came to be used in some circumstances as a feminine) and derivatives or compounds of diēs, such as.

Declension paradigm
Other than and, most fifth declension nouns are unused or uncommon in the plural. In particular, genitive plural forms other than diērum, rērum and dative/ablative plural forms other than diēbus, rēbus are rare, although some occur; nominative or accusative plural forms in -ēs are somewhat less rare.

There is a closed set of locative singular forms in -ē, mainly temporal expressions: examples include, ,. When used in isolation, forms like these can be analyzed as adverbs rather than nouns: however, their original status as locative-case nouns is shown by expressions that contain an agreeing adjective in the locative case. Aulus Gellius (Noctes Atticae 10.24) describes expressions such as "diequinti"/"diequinte" as compound adverbs ("adverbio copulate") and attributes their use to to the time of Cicero and his predecessors.

Examples
Ending in -iēs: Ending in consonant + -ēs:
 * diēs, diēī
 * speciēs, speciēī
 * rēs, reī
 * fidēs, fideī,