Summary

part of speech				Latin	English
verb	-	-	-	ago	-
subjective noun	S	N	S	actor	actor
subjective adjective	S	A	P	agax	agacious
objective noun	O	N	P	agendus	agend
objective adjective	O	A	S	actabilis	actable
present participle	S	A	P	agent	agent
perfect participle	O	A	S	actus	act
supine	-	N	S	actum	action

The three columns in the middle tell whether the part of speech is

subjective (S) or objective (O);

a noun (N) or an adjective (A);

derived from the present stem (P) or the supine (S).

I should point out that “subjective” and “objective” are made-up names that indicate whether the part of speech refers to a subject or object of the verb.

In addition to deriving nouns and adjectives from verbs, as above, it is also possible to derive nouns from adjectives, and vice versa.

The most important method for doing so is not really a derivation at all, it is just the simple fact that adjectives can, without modification, be used as nouns. That method was used to produce the objective noun from the gerundive, and is also commonly used to produce nouns from the two participles.

Two other methods, using the suffixes “-ius” and “-itas”, are described in the essay on the subjective adjective.

Applying the methods as widely as possible, we obtain the following.

gerundive	O	A	P	agendus	-
from present participle	S	N	P	agent	agent
from perfect participle	O	N	S	actus	act
from subjective noun	S	A	S	actorius	actory
from subjective adjective	-	N	P	agacitas	agacity
from objective adjective	-	N	S	actabilitas	actability
from present participle	-	N	P	agentitas	agency (?)