§89. Adjectives from the Perfect Base (-ORIUS, -IVUS)

1. Just as nouns can have an adjectival suffix in -arius (§38), so can the perfect participle base take a similar adjective-forming suffix in -orius; in its neuter -orium form, it too can mean “a place for.” The -orius adjective appears as English laudatory, amatory, exclamatory, expository, etc. The noun is seen in auditorium, moratorium (“delay”), dormitory, laboratory, lavatory, conservatory, observatory, and purgatory (“cleanse”).

2. The perfect participle could also assume the suffix -ivus, which originally meant “tending to.” Thus from agere, actus came activus (E active, “tending to do”), and from fugere, fugitus came fugitivus (E fugitive, “tending to run away”). The suffix is common in English: motive, captive, decisive, incisive, evocative, deductive, inductive, seductive, putative, interrogative, infinitive, derivative, denominative.