Nouns

(n)modal auxiliary verb, modal auxiliary, modal verb, modalan auxiliary verb (such as ‘can’ or ‘will’) that is used to express modality

Adjectives

(s)modal, averagerelating to or constituting the most frequent value in a distribution“the modal age at which American novelists reach their peak is 30”
(a)modalof or relating to a musical mode; especially written in an ecclesiastical mode
(a)modalrelating to or expressing the mood of a verb“modal auxiliary”