From prōmptus (“readiness”) + -ārium (of purpose), via *promptuārius. The u in the spelling is due to the fourth declension noun.
prōmptuārium n (genitive prōmptuāriī or prōmptuārī); second declension
Second-declension noun (neuter).
Case | Singular | Plural |
---|---|---|
Nominative | prōmptuārium | prōmptuāria |
Genitive | prōmptuāriī prōmptuārī1 |
prōmptuāriōrum |
Dative | prōmptuāriō | prōmptuāriīs |
Accusative | prōmptuārium | prōmptuāria |
Ablative | prōmptuāriō | prōmptuāriīs |
Vocative | prōmptuārium | prōmptuāria |
1Found in older Latin (until the Augustan Age).