Some verbs have what appears to be the wrong morphology for voice (active versus passive) for part of their paradigm.
For a description of fully deponent verbs, see this page.
Some verbs are deponent for only a portion of the paradigm.
In some verbs there is a difference between the present and perfect forms. This is perhaps not surprising, given the distinct origins of the different stems. In Indo-European, only the ancestor of the Latin present stem forms displayed a contrast between active and mediopassive forms. The Indo-European perfect, ancestor of the Latin perfect active, was a kind of resultative present, while the supine stem forms descend from Indo-European verbal adjectives in -t-, which had a passive or resultative sense. These forms were independent of the voice alternation found in the present, but presumably interacted with the lexical semantics of individual verbs to produce apparent shifts in diathesis.
The canonical semi-deponents, the four intransitive verbsaudeō 'dare', gaudeō 'rejoice', fidō 'trust', soleō'be wont', have deponent perfect forms, illustrated below with audeō (only 3rd person singular and nominative singular masculine forms are shown):
| active form | passive form | ||
| A. | PRS IND | aud-et | |
| IMPRF IND | aud-ēbat | ||
| FUT IND | aud-ēbit | ||
| PRS SBJV | aud-eat | ||
| IMPRF SBJV | aud-ēret | ||
| IMP PRS | aud-ē | ||
| IMP FUT | aud-ētō | ||
| INF PRS | aud-ēre | ||
| B. | PRF IND | aus-us est | |
| PLUPRF IND | aus-us erat | ||
| FUT PRF | aus-us erit | ||
| PRF SBJV | aus-us sit | ||
| PLUPRF SBJV | aus-us esset | ||
| INF PRF | aus-us esse | ||
| PART PRF | aus-us | ||
| C. | SUPINE | aus-um | |
| INF FUT | aus-ūr-us esse | ||
| PART FUT | aus-ūr-us | ||
| PART PRS | aud-ēn-s | ||
| GERUND | aud-end-ī | ||
Further, there are a number of impersonal verbs which are semi-deponent in earlier texts, but not in later ones:
| earlier perfect | later perfect | ||
| libet | libitum est | libuit | 'it is pleasing' |
| licet | licitum est | licuit | 'it is permitted' |
| miseret | miseritum est | miseruit | 'it distresses' |
| piget | pigitum est | piguit | 'it displeases' |
| pudet | puditum est | puduit | 'it causes shame' |
| taedet | taesum est | taeduit | 'it disgusts' |
There is a small class of intransitive verbs, the most prominent of which is revertor 'return', which behave as deponents except in the perfect. They have a normal perfect active stem, and the forms that one would expect to be built off it. Thus, for every perfect value where there is a morphological opposition between active and passive, these verbs have an active form. As a result, the perfect participle, which has no active form, is found with these verbs, and it has an active value, as typical of deponent verbs. A fragment of the paradigm of revertor is given below:
| active form | passive form | |
| PRS IND
(present stem) |
revertor 'I return' |
|
| PRF IND
(perfect active stem) |
revertī 'I returned' |
|
| PART PRF (supine stem) |
reversus 'having returned' |
Other verbs behaving this way include dēvertor 'turn aside' (same stem as revertor), paciscor '(make a) contract' (perfect pepigī) and assentior (perfect assensi)
The present stem passive forms of the verb faciō 'do' are based on the stem fi-, which is morphologically passive in the infinitive, but active in the other forms:
| active | passive | ||
| present stem | PRS IND | fac-it | fi-t |
| IMPRF IND | fac-iēbat | fī-ēbat | |
| FUT IND | fac-iet | fī-et | |
| PRS SBJV | fac-iat | fī-at | |
| IMPRF SBJV | fac-eret | fi-eret | |
| IMP PRS | fac(-e) | fī | |
| IMP FUT | fac-itō | fī-tō | |
| INF PRS | fac-ere | fi-erī | |
| perfect stem | PRF IND | fēc-it | fact-us est |
| PLUPRF IND | fēc-erat | fact-us erat | |
| FUT PRF | fēc-erit | fact-us erit | |
| PRF SBJV | fēc-erit | fact-us sit | |
| PLUPRF SBJV | fēc-isset | fact-us esset | |
| INF PRF | fēc-isse | fact-us esse | |
| PART PRF | fact-us | ||
It is not entirely clear what the relationship of fi- to faciō is. Is fi- a suppletive stem within the paradigm of faciō, or are fi- to faciō two defective lexemes in loose association with each other? The complementarity of their paradigms suggests suppletion: fi- has all and only the forms that faciō lacks. On the other hand, in some contexts the meaning of fi- is so semantically distinct as to suggest it is a different lexeme. Etymologically, it was, fi- having been a form of the verb 'to be', and the sense 'be, become' is still apparent in some of its uses, e.g. fiat lux 'let there be light'.
Under either interpretation one can speak of semi-deponency. If fi- is a suppletive stem of faciō, then the passive of the present, imperfect and future (indicative, subjunctive and imperative) is morphologically active. If fi- is a defective active verb distinct from faciō, then it is semi-deponent in that its infinitive is morphologically passive.
Likely as not, fi- has a dual status. Some evidence for this might come from the phenomenon of 'voice attraction' (voice attraction occurs where form of the auxiliaries coepi 'begin' and desino 'stop' matches the functional/semantic voice of the main verb it is construed with; see this page for a discussion.) Kühner (1955: 677-78) notes that the infinitive fierī is construed with both active and passive forms of coepi. Though he does not specifiy the conditions for variation, the examples he gives where fierī is construed with the passive of coepi appear to invole fierī as the passive of faciō, while examples one can find of fierī construed with the active of coepi appear to involve another lexeme with the meaning 'be, become':
fi- as passive of faciō:| quiescenti | plebi | ab | iunioribus | patrum |
| being.quiet.ABL.SG | plebians.ABL.SG | by | younger.ABL.PL | father.GEN.PL |
| iniuriae | fieri | coeptae |
| injury(F).NOM.PL | do.INF.PASS | begin.PART.PRF.PASS.F.NOM.PL |
| 'While the plebians were staying quiet, injuries began to be done [to them] by the younger patricians.' [coeptae should be understood as elliptical for the perfect passive coeptae sunt 'they were begun'] |
||
| plura | fieri | iudicia | coeperunt |
| more.N.NOM.PL | be.INF.PASS | justice(N).NOM.PL | begin.PRF.3PL |
| 'Judicial speeches began to become more numerous. | |||
However the status of fi- is construed, there is an important morphological point worth noting. The alternation between active and passive morphology with fi- is independent of any stem alternation. In all the other instances of semi-deponency in Latin, this alternation is concommitant with a stem alternation.
Flobert, Pierre.1975. Les verbes déponents latins des origines à Charlemagne. Paris: Société d’Édition 'Les Belles Lettres'.
Ernout, Alfred and François Thomas. 1953. Syntaxe latine (2nd edition). Paris: Klincksieck.
Kühner, Raphael. 1955. Ausführliche Grammatik der lateinischen Sprache (part 2, 1, revised by Andreas Thierfelder). Hamburg: Hahn.