Definition of modal verb in English:

modal verb

Pronunciation /ˈmōdl vərb/ /ˈmoʊdl vərb/ /məo͝odlˈvɜːb/ /məʊdlˈvɜːb/

noun

Grammar
  • An auxiliary verb that expresses necessity or possibility. English modal verbs include must, shall, will, should, would, can, could, may, and might.

    ‘He shook his head impatiently. ‘We instruct the computer to ignore what we call grammatical words - articles, prepositions, pronouns, modal verbs, which have a high frequency rating in all discourse.’
    • ‘The negative modal verb maun't (mustn't) is sometimes used in rural areas, but the positive form maun, as used in Scots and in Northern Ireland, is rare.’
    • ‘That minimum is represented in English by verbs such as must and ought, which are modal verb with no preterite (inflected past tense).’
    • ‘Secondly, all the various kinds of modality can be expressed (some more idiomatically than others) without the use of the modal verbs.’
    • ‘Did he really say that the modal verb form might was being eliminated in favor of may and ‘has practically disappeared from the language’?’