-osus

• -ossus (older form)
• -ōnsus (found in formōnsus, possibly the result of hypercorrection)

Likely reflects a derivation *-h₃d-s-o- from Proto-Indo-European *h₃édos ~ *h₃édesos (“smell”),^[1][2] whence odor. Originally meaning “smelling like”, as evidenced possibly by hircōsus (“smelling like a goat”) and vinōsus (“fond of wine, *reeking of wine?”), it would have later generalised into “full of”. Compare related Ancient Greek -ώδης (-ṓdēs, “smelling like; full of”) and Old Armenian -ոտ (-ot) which underwent the same semantic change.

Alternatively, a derivation from Proto-Indo-European *-wénts has also been proposed, through a form such as *-wont-to- by suffixation of *-tós.^[3]

• (Classical Latin) IPA^(key): [oː.sʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [o.s̬us]

-ōsus (feminine -ōsa, neuter -ōsum); first/second-declension suffix

1. -ose, -ous; full of, overly, prone to. Used to form adjectives from nouns.

   ‎nervus (“sinew, energy”) + ‎-ōsus → ‎nervōsus (“nervous”)

   ‎racēmus (“cluster, bunch”) + ‎-ōsus → ‎racēmōsus (“racemose”)

   ‎ventus (“wind”) + ‎-ōsus → ‎ventōsus (“windy”)

First/second-declension adjective.