Auxiliary is defined as something or someone used in a supporting role or used in reserve.
(Modal auxiliary verb, defective) To be possible, usually with be.
To be allowed or permitted to:
Should signifies something you ought to do or something that is a good idea or that something that may happen.
Something that is absolutely required or indispensable:
Shall is another way of saying should.
Used to express determination, compulsion, or obligation
an auxiliary verb (such as `can' or `will') that is used to express modality
Find another word for modal-auxiliary. In this page you can discover 13 synonyms, antonyms, idiomatic expressions, and related words for modal-auxiliary, like: auxiliary, ought, can, may, should, auxiliary-verb, must, shall, will, would and modal auxiliary verb.