From many verbs one can derive an agent noun for each gender:

  • computare > computator (m), computatrix (f), computatrum (n)
  • scribere > scriptor, scriptrix, scriptrum

Some of these derivatives are rarely found, but it is easy enough to derive productively when needed — when the perfect participle stem ends in a t. It is easy to speak about male and female lecturers, for example (lector and lectrix).

How to derive feminine an neuter agents from a verb whose perfect participle stem ends in an s? The masculine derivative is common and easy (e.g. profiteri > professor), but how to form the feminine and neuter versions? I would like this to be analogous with the derivatives for computare and scribere above, so using the present participle (e.g. profitens) is unsatisfactory.

If you can give a way to derive feminine and neuter agents, please give actual use examples. Examples should preferably be classical. If there are no classical examples, are there later ones and did ancient grammarians notice that such words are missing?

Here is a feeble attempt to derive in feminine and neuter: The stem of profiteri is profit- and when we add a t for perfect participle, we get profitt- which has turned into profett- and then profess-. It seems easier to derive before making the substitution tt > ss. The companions of profettor would then be profettrix and profettrum. Intervocalic tt should become ss, but it feels more natural to take ttr > tr. This leaves me with professor, profetrix and profetrum. This is my best guess, but I have no idea if this is consistent with classical (or any other) use of Latin.

  • Not so relevant to the meat of your question, but I checked and both Oxford (gazette.web.ox.ac.uk/files/encaenia2022-1tono5355pdf) and my copy of Harrius Potter et Philosophi Lapis use masculine professor for women professors.
    – dbmag9
    Jul 4 at 12:19
  • @dbmag9 That would actually make a nice answer to this related question.
    – Joonas Ilmavirta
    Jul 5 at 13:19
  • It turns out I checked the Encaenia speeches last year in my answer to that question (they are an absolute pleasure to skim through); the Harry Potter part hadn't occurred to me then.
    – dbmag9
    Jul 5 at 13:30

2 Answers 2


There are indeed a few examples of such words from ancient texts, but they are very rare. They are still formed from the supine stem, meaning that the original dental consonant (d or t) is replaced with s, to which -trix or -trum is then appended.

The Perseus Project provides a search tool for its dictionaries (in particular, Lewis & Short) which allows searching for lemmas by their last few letters. The search results for -strix and -strum list all candidate words; beware, though, that each result also contains a number of unrelated entries (i.e. words derived in other ways).

For the feminine, the least uncommon word (according to Perseus) is tonstrix, which appears three times in Plautus (preclassical), once in Martial (postclassical), and also in one inscription. (Furthermore, there is the variant tonsrix mentioned once by the grammarian Charisius.) According to the grammarian Priscian, Cicero once used defenstrix. Hence, there is relatively good evidence for this derivation having been used over a long period.

Of specific interest regarding profiteri, which has a double -ss- in its supine, are assestrix (compare assessor) and possestrix (compare possessor), demonstrating that -ss- is simplified to -s-. Both words were used by the poet Afranius (early first century BC), according to grammarian Nonius Marcellus.

We can therefore conclude that the female equivalent to professor would likely have been profestrix.

Among the words ending in -strum found in the search, I can only identify two examples that actually match the pattern and are derived from a supine stem ending in -s: claustrum (from claudere) and rostrum (from rodere). On the plus side, both are quite common, at least in plural. There are no examples for verbs with -ss in the supine. Still, it seems plausible to me that the corresponding word derived from profiteri would have been profestrum.

  • 5
    Many thanks! This is an excellent answer. I had not realized that claustrum and rostrum were derived this way, but it makes sense now.
    – Joonas Ilmavirta
    Feb 25, 2016 at 10:56

As chirlu says, the usual way to form a feminine equivalent to a noun in -(s)sor is with -strix. Aside from the examples mentioned in that answer, here are further words of this form found using Logeion's reverse search tool:

There isn't really a neuter version of this suffix; there are several suffixes, some related and some unrelated, used to derive neuter instrument nouns

The commentary on Virgil's Aeneid by Servius (or Pseudo-Servius?), when discussing the form victricia, explicitly states that masculine -tor and feminine -trix have no neuter counterpart in the singular, and that the neuter version in the plural ends in -icia (used adjectivally in Virgil):

victricia omnia nomina a verbo venientia cum in 'or' exeunt, masculina sunt, ut victor; cum in 'trix', feminina sunt, ut victrix; neutra vero non faciunt, nisi tantum ex numero plurali: unde est victricia.

(Book 3)

The suffix -trum

There is a neuter suffix -trum, but unlike -trīx, it does not form nouns that are synonymous aside from gender with masculine nouns in -tor. The suffixes -tor and -trīx both form agent nouns. But neuter words in Latin almost always refer to inanimate things rather than beings with agency, and so in the words where -trum appears, rather than denoting an agent, it instead denotes a tool or instrument. We see this in one of the few cases of a pair of -tor and -trum words, arātor "ploughman" and arātrum "plough".

However, -trum was never a very productive instrument noun suffix in Latin. One reason might be that it appears to have originally occurred only in specific phonological contexts: when there was an /r/ or /l/ sound earlier in the word, or when there was an immediately preceding /s/ sound (and actually, I think even the -strum words more often than not have a preceding /r/ or /l/ sound; not sure if that's a coincidence). For more on this restricted pattern, which seems to be old, see the question Suffixes -τρον, -θρον, and -εθρον. Profess- technically meets both of these criteria, if you include the prefix, so profestrum does seem at least supportable by analogy (moreso in fact than the already-coined neologism "computātrum"), although it's unclear what an instrument or tool noun corresponding to "professor" would be.

Neuter instrument suffixes other than -trum: -culum/-crum, -tōrium, -mentum

In general, the suffix -culum (ultimately from the same etymological source as -trum) appeared on a greater number of Latin instrument nouns than -trum (although neither suffix was as productive as -tor ended up being). When preceded in the same word by -l-, -culum frequently undergoes dissimilation and becomes -crum.

Usually, -culum attaches to the present stem of the verb (possibly with changes in the preceding vowel), rather than being built on the perfect participle stem. So for example, from offendo, -di, -sum there is offendiculum. An example derived from a second conjugation verb is irrīdĭcŭlum. This suggests that *profiticulum should be possible, at least in form; however, I don't like the look or sound of it.

In later Latin (especially), the compound suffix -tōrium becomes somewhat common and productive for forming nouns for tools or instruments, such as cōnflātōrium "furnace" and pūnctōrium "instrument for pricking". From profiteri, we would expect *professōrium.

The suffix -mentum also comes to be used sometimes in later Latin to form words for tools or instruments, such as involūmentum in Augustine for classical involūcrum "wrapper, covering, envelope". I believe adding this suffix to profiteri would most likely yield *profitumentum (like documentum, monumentum; this vowel is what etymologists call the "sonus medius" and so a variant in -imentum might also be possible).

Overall, I would say there is no systematic parallelism between -tor and any neuter ending the way there is between -tor and -trīx.

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