Viri is the plural of the masculine 2nd declension noun vir, which means 'man'. Vir 'man' is a masculine noun and the -i ending is appropriate for the plural nominative of masculine second declension nouns. Octopus comes from the Greek, so the-us ending does not mark a Latin masculine noun of the second declension.iri is the plural of the masculine 2nd declension noun vir, which means 'man'. Vir 'man' is a masculine noun and the -i ending is appropriate for the plural nominative of masculine second declension nouns. Octopus comes from the Greek, so the-us ending does not mark a Latin masculine noun of the second declension.