7.7 - Nominal verb forms
Verbs also have five nominal forms: three participles and two infinitives.
The participles are: imperfect, perfect and virtual, also labelled present participle, past participle and verbal adjective in traditional grammars. Regardless of the traditional names, the difference between imperfect and perfect participle is of aspect, not tense. The verbal adjective is equivalent to English "-able" adjectives.
The infinitives are: imperfect and perfect, or present and past, also with an aspect distinction.