Is the third person passive perfect of a verb a source of nouns, e.g. "benedictus" from "bendico"?

Question

I always get confused with benedictus. It Christian prayers, it is found both as a noun and as a (passive) verb, e.g. benedictus est. When est is omitted (not uncommon in Latin, it seems), both look identical.

This issue made me think that there might be some connection between the two forms. In particular, that the verb "produced" the noun. So, consider (non-deponent?) verbs in their third person singular passive perfect conjugation. For the verb benedico, such conjugation is benedictus est. Is the latter the etymological origin of the noun benedictus? Well, this noun means "a blessed person", this is, "someone who has been blessed" (aliguis quod benedictus est?). So there might be some sort of connection. Is this true? Is this a general rule for nouns ending in -us that are related to a verb? Other examples I have found (without trying to be exhaustive) are discursus, intellectus, loricatus, observatus.

Now, not all verbs whose passive perfect ends with -us have a related noun ending in -us. Some are close to a noun ending in -or. For instance, for the verb administro, with passive perfect administratus, there is the noun administrator. Similar with fabrico/fabricator, habito/habitator, loquor/loqutor, etc.

So, is there a connection (and perhaps a precedence) between the passive perfect conjugation and the noun for words with a common base?

Answer 1

They come from the same source, in this case.

The noun benedictus is a substantive: that is, an adjective on its own, acting as a noun. This is very common in Latin, and also shows up sometimes in English, as in "the good, the bad, and the ugly".

The adjective benedictus, meanwhile, is a participle: a special form of a verb that acts like an adjective. There are three of these in Latin, and this is probably the most common, the perfect passive participle. It's equivalent to the English participle "bless-ed", and actually comes from the same PIE source.

The verb benedictus est is a periphrastic. There are some verb forms that are just morphologically missing in Latin, for no apparent reason. So when writers needed to express a perfect passive meaning, they took the one perfect passive thing they had (the participle), and combined it with a form of sum to make it a verb. This is how English makes all its passives, since English has no passive morphology at all: "he is blessed", "she was blessed", and so on. Latin uses it only for a few missing passive forms (perfect, pluperfect, and future perfect).

There are also derivations: nouns created from verb stems by using various special suffixes (like the -or you mention). One of these, confusingly, involves putting -us on the fourth principal part; this is how we get cursus "course" from currō "run". You can tell the difference because this derivation is fourth declension feminine (cursus, -ūs, f), while the participle is second declension masculine (benedictus, -ī, m).