, a defective verb
is a verb
with an incomplete conjugation
. Defective verbs cannot be conjugated in certain tenses
, or moods
Defective verbs in English
The most commonly recognized defective verbs in English are the class of preterite-present verbs
, and will
(which was not historically a preterite-present but has joined the class in modern English). Though these verbs were not originally defective, in most varieties of English today, they occur only in a modal auxiliary
sense. However, unlike normal auxiliary verbs, they are not regularly conjugated in the infinitive mood. Therefore, these defective auxiliaries do not accept each other as objects. Additionally, they do not regularly appear as participles.
For example, can lacks an infinitive, future tense, participle, and gerund. The missing parts of speech, however, can be expressed by using the appropriate forms of to be plus able to. So, while I could do it and I was able to do it are equivalent, one cannot say *I will can, *I have canned, or *canning do it, but would still be able to say I will be able to, I have been able to, and being able to do it. Likewise, the role of must, which like can/could has only a present and a past tense (which is also must), can be filled in by to have plus to. This way, one can say things like he will have to clean the room next week, which would be impossible to do with must.
Beyond the modal auxiliaries, beware is a full-fledged defective verb of English: it is used as an imperative (Beware of the dog) and an infinitive (I must beware of the dog), but very rarely or never as a finite verb, especially with inflectional endings (*bewared, *bewares). Certain other verbs are defective only in specific constructions.
Impersonal verbs in English
Impersonal verbs such as rain and snow share some characteristics with the defective verbs in that conjugations such as I rain or they snow are not often found; however, the crucial distinction is that impersonal verbs are "missing" certain forms for semantic reasons — in other words, the forms themselves exist and the verb is capable of being fully conjugated with all its forms (and is therefore not defective) but some forms are unlikely to be found because they appear meaningless.
Nevertheless, native speakers can typically use and understand metaphorical or even literal sentences where the "meaningless" forms exist, such as:
Contrast the impersonal verb rain (all the forms exist even if they sometimes look semantically odd) with the defective verb shall (only I shall and I should are possible):
| I rain
|| I shall |
| I rained
|| I should |
| I am raining
|| *I am shalling (not a possible conjugation) |
| I have rained
|| *I have should (not a possible conjugation) |
| to rain
|| *to shall (not a possible conjugation) |
Defective verbs in Latin
Latin has defective verbs that possess forms only in the perfect tense system; such verbs have no present tense forms whatsoever. However, these verbs are present in meaning. For example, the first-person form odi and infinitive odisse appear to be the perfect tense of a verb such as *odo/odio, but in fact have the present-tense meaning "I hate". Similarly, the verb memini, meminisse is conjugated in the perfect:
Instead of "I remembered", "you remembered", etc., these forms signify "I remember", "you remember", etc. Latin defective verbs also possess regularly formed pluperfect forms (with a simple past tense meaning) and future perfect forms (with a simple future tense meaning). Compare deponent verbs, which are passive in form and active in meaning.
Examples from other languages
- French: frire ("to fry", lacks non-compound past forms), éclore ("to hatch", theoretically lacks an imperfect, although speakers easily fill it in)
- Spanish: abolir (forms such as *abole, for example); balbucir (forms that would have -zc-, such as *balbuzco).
- Polish: widać ("it is evident"), słychać (the only form of these verbs that exists is the infinitive)
- Portuguese: a large number of Portuguese verbs are defective in person, i.e., they lack the proper form for one of the pronouns in some tense. The verb colorir ("to color") has no first-person singular in the present (thus requiring a paraphrase, like estou colorindo ("I am coloring") or the use of another verb of similar meaning, like pintar ("to paint").
- Dutch: in Dutch there are four defective verbs (apart from deponent verbs and impersonal verbs): plegen (to be used to), zullen (shall), zijn (to be) and wezen (to be). The verbs zullen and plegen do not have any perfect tenses. Furthermore, zullen does not have any future and past future tenses, and its conditional mood does not exist. The verbs zijn and wezen are used to complete each other's conjugation. Apart from the infinitive (zijn versus wezen (to be)) and gerund (het zijn versus het wezen ((the) being)), only the simple present subjunctives of both verbs exist (ik zij versus ik weze (I be)). For all other forms, there only exists one form: e.g. zijnde (being) (present participle of zijn), ik was (I was) (indicative past simple of wezen). (See Dutch conjugation)
- Swedish: The auxiliary måste (must) lacks the infinive, except in Swedish dialects spoken in Finland. Also, this verb is unique in having identical present and past tense forms.
- Korean: 말다 (to stop or desist) may only be used in the imperative form, after an 'action verb + 지' construction. Within this scope, however it can conjugate for different levels of politeness; e.g. 하지마! (Stop that!); 하지마십시오 ('Please, don't do that').
- Irish: arsa (says/said), can only be used in past or present tenses. Copula is lacks a future tense, imperative mood and conditional mood.