As you will have come to expect by now, Latin has various systematic ways of transforming verbs into other parts of speech. In these new Latin words, the semantic action of the original verb will still be evident; but instead of having a purely verbal function, such as “carry,” “hear,” “teach,” “feel,” or “make,” the word will now convey some additional meaning, like “the act of carrying” or “able to be heard” or “the person who teaches” or “the state of feeling” or “a thing made.” In its native Germanic tradition, English is quite limited in its capacity to form new parts of speech this way. For just that reason, vast numbers of Latin verb derivatives have been borrowed over the centuries, to become basic and indispensable English words. If you can learn to understand the relationship between these words and the Latin verbs from which they arose, you will begin to control enormous categories of English vocabulary.
A good many of these verb-derived categories consist of standard Latin noun types, which English has borrowed with only minor adaptations. Because they are standard, they are consistent and predictable. If you know a particular Latin verb such as capere, captus, you will be able with some confidence to construct its related noun forms—captio, captura, captor; and then, no doubt, you will spot the connection between those forms and a variety of English words. Soon you will be able to reverse the procedure, predicting the Latin etymon of any English noun that belongs to a familiar type.
All this verb manipulation will involve one or other of the two key forms that we met in Chapter 9 (§62)—the present infinitive and the perfect participle. The PERFECT PARTICIPLE is particularly useful as an instrument for creating Latin nouns, either by itself or as a base to which various suffixes may be added. To obtain the base of any Latin perfect participle, just remove the -us ending. The Latin perfect participle is actually a 1st and 2nd declension adjective in -us, -a, -um. The form mutatus, for example, is a verbal derivative that means “changed”, and it can be used as a pure adjective in phrases such as vir mutatus, “a changed man,” or femina mutata, “a changed woman.”