§193. The Periphrastic Conjugations
A Periphrastic form, as the name indicates, is a “roundabout way of speaking.” In the widest sense, all verb-phrases consisting of participles and sum are Periphrastic Forms. The Present Participle is, however, rarely so used, and the Perfect Participle with sum is included in the regular conjugation ( amātus sum, eram, etc.). Hence the term Periphrastic Conjugation is usually restricted to verb-phrases consisting of the Future Active Participle or the Gerundive with sum.
J. H. Allen and J. B. Greenough, New Latin Grammar (Boston: Ginn, 1903). Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities.