What is the fifth latin declension?

Answer 1

The fifth declension is a small group of nouns, sometimes referred to as "e-stems," that end in -ēs (or -iēs) in the nominative singular and -eī (or -iēī) in the genitive singular. Though there were not many of these, they were common, and included diēs, "day," and rēs, "thing, matter, affair." Except for these two, nouns in this declension were defective, which means they did not appear in all possible forms. Most lacked a plural, or occurred in the plural only in the nominative and accusative cases.

Fifth-declension nouns were feminine with the exception of diēs, which was usually masculine except when it referred to a specific day or date (e.g., diē constitūtā, "on the appointed day").

Answer 2

The Latin word for "fifth" is the adjective quintus, -a, -um. The fraction "one fifth" is quinta pars (literally "a fifth part").

The word Quintus was also used as a name for a family's fifth-born son. The famous Roman orator Marcus Tullius Cicero, for example, had a brother named Quintus.