-enus

Ultimately from Proto-Indo-European *-nós:

• In sense 1, from the distributive numeral suffix -nus by rebracketing of numerals such as septēnus (“seven each”), novēnus (“nine each”), dēnus (“ten each”).
• In sense 2, an extended form of the relational suffix -nus; compare -ānus, -īnus.
• In sense 3, borrowed from Ancient Greek -ηνός (-ēnós).

• (Classical Latin) IPA^(key): [eː.nʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [e.nus]

-ēnus (feminine -ēna, neuter -ēnum); first/second-declension suffix

1. alternative form of -nus, used to form some distributive numerals.

   ‎centum (“hundred”) + ‎-ēnus + ‎-enus → ‎centēnus (“one hundred each”)

   ‎septingentī (“seven hundred”) + ‎-ēnus + ‎-enus → ‎septingentēnus (“seven hundred each”) (alternative form of septingēnus)

   ‎mille (“thousand”) + ‎-ēnus + ‎-enus → ‎millēnus (“one thousand each”)

   ‎quot (“how many”) + ‎-ēnus + ‎-enus → ‎quotēnus (“how many each”)

2. (rare) Of or pertaining to; -ine

   ‎lanius (“butcher”) + ‎-ēnus → ‎laniēnus (“of a butcher”)

   ‎alius (“other, another”) + ‎-ēnus → ‎aliēnus (“of another; alien; foreign”)

3. Added to a place name to form an adjective.

   ‎Antiochīa (“Antioch”) + ‎-ēnus (“Antiochian”) → ‎Antiochēnus

First/second-declension adjective.