The most commonly recognized[citation needed] defective verbs in English are auxiliary verbs—the class of preterite-present verbs—can/could, may/might, shall/should, must, ought, and will/would (would being a later historical development).
Though these verbs were not originally defective, in most varieties of English today, they occur only in a modal auxiliary sense.
Some verbs are becoming more defective as time goes on; for example, although might is etymologically the past tense (preterite) of may, it is no longer generally used as such (for example, *he might not go[a] to mean "he was forbidden to go").
Similarly, should is no longer used as the past of shall, but with a separate meaning indicating possibility or moral obligation.
Nevertheless, native speakers can typically use and understand metaphorical or even literal sentences where the "meaningless" forms exist, such as I rained on his parade or She doesn't frost cakes, she snows them.
The implicit repetition intrinsic to the meaning of soler results in it only having forms in the present and imperfect tenses.
Defective verbs in Catalan can generally also be used in the impersonal forms of the infinitive, gerund, and past participle.
All other forms, including the infinitive, have long become obsolete and are now unknown and unintelligible to modern speakers.
It remains commonplace in the closely related Dutch language as verkiezen; for example, Verkiezingen in Nederland (Elections in the Netherlands).
[3] The verb χρή (khrē, 'it is necessary'), only exists in the third-person-singular present and imperfect ἐχρῆν / χρῆν (ekhrēn / khrēn, 'it was necessary').
The verbs munu 'will' and skulu 'shall' also end in a vowel other than -a and lack all past indicative forms.
Both verbs lack numerous inflected forms, with entire tenses and voices missing altogether.
Defective verbs in the related Besemah language (South Barisan Malay), for example, have been explained by McDonnell (2016).
For example Widać blask wśród drzew 'A glow is visible among the trees' or Jego głos słychać w całym domu 'His voice can be heard in the whole house'.
A large number of Portuguese verbs are defective in person; that is, they lack the proper form for one of the pronouns in some tense.
Some Russian verbs are defective, in that they lack a first person singular non-past form: for example, победить 'to win', убедить 'to convince', дудеть 'to play the pipe'.
These are all verbs whose stem ends in a palatalized alveolar consonant;[6] they are not a closed class, but include in their number neologisms and loanwords such as френдить (to friend, as on a social network).
[citation needed] Many experiential verbs describe processes that humans cannot generally undergo, such as пригореть 'to be burnt, regarding food', куститься 'to grow in clusters', and протекать 'to seep'—are ordinarily nonsensical in the first or second person.
[8] However, this is a semantic constraint rather than a syntactic one; compare the classic nonsensical-but-grammatical sentence Colorless green ideas sleep furiously, or more directly, the English phrase I am raining.
The auxiliary verb måste 'must' lacks an infinitive, except in Swedish dialects spoken in Finland.
Some of the more common ones in everyday use include dylwn ("I should/ought"), found only in the imperfect and pluperfect tenses, meddaf ("I say"), found only in the present and imperfect, and geni ("to be born"), which only has a verb-noun and impersonal forms; for example, Ganwyd hi (She was born, literally "one bore her").
Common defective verbs in the spoken language are eisiau (pronounced, and often spelt, as isio or isie) and angen which mean 'to want' and 'to need' respectively; both are in fact nouns but are used in speech as if they were verb-nouns though they do not take the preceding yn, compare dw i'n canu 'I sing' vs. dw i eisiau 'I want'.
The literary language would use these as nouns and not as defective verbs; for example, mae eisiau arnaf 'I want', literally 'there is a want on me'.