Meaning and definition of modal auxiliary verbs

In english grammar, there are three types of auxiliary verbs — “linking auxiliaries, helping auxiliaries, and modal auxiliary verbs.” Among these, modal auxiliary verbs are mainly used to express various types of moods like, “possibility, permission, request, or necessity”. In this blog, I’m going to clarify the meaning and definition of modal auxiliary verbs with suitable examples.

“Like linking and helping verbs, the ambit of functioning of modal auxiliary verbs is also vast, and needs thoroughly learning”.

Modal auxiliary verbs–

•What is  “PRAN” ?

•Possibility—May, Will, Could, Might

•Permission-May, Can


Requet–Can, Could, would, may

•Ability–Be able to, Can, Could

•Advice–Should, Ought to

•Necessity, Obligation–Have to, Must

Here is an easy tactics of define the total modal auxiliary verbs one by one.

May, will, could, and might are especially used to express likeliness or possibility in present or future. It mere shows likeliness not certainty. However, not all four express same degree of possibility.

‘May’ express stronger possibility, whereas “can’ shows minor possibility. ‘Could’ is used in for past possibility. Besides, might expresses milder. In addition, will is preferred for certain prediction in future.

Permission–May, Can

Both express permission with varying degrees. Here, we need to understand permission at both ends.

If you are going to take permission; then, ‘may’ is preferred. But, to grant permission, usually ‘can’ is used ; for example, may I use your mobile?  Yes, you can. For deeper insight, you will learn in the next post.

Request–May, Could, Would

In order to make polite request, ‘could’ is usually preferred; on the other hand, ‘may’ is used for formal request.’Would’ is another modal auxiliary to express request.

Ability–Can, Could, be able to

There are two types of abilities- general and specific. In order to express strong ability ‘be able to’ is used after helping verbs.

For general possibility-may, could, can, and might are used. On the other hand, for specific possibility- ‘be able to’ is used after helping verbs according to the tense.

We use ‘can’ to show self ability, whereas, ‘may’ is indicates others abilities.

Advice–Should, ought to

Generally, should is used for common advice. It means that it is common everywhere for general advice. On the other hand, ought to expresses moral advice or obligations. It is highly useful in respect to moral duties or obligations.

Necessity or obligation–Have to, must

‘Must’ implies necessity, ‘but have to’ express compulsions to do something. Generally, ‘must’ is common in family interaction; on the other hand, ‘have to’ is more applicable in social relationship.

I hope through this blog, “Meaning and definition of modal auxiliary verbs” you will understand the purpose and application of modal auxiliaries in the day to day interactions.

Adversative coordinating conjunctions

Functions of preposition

Modal verbs for obligation

Role of modal auxiliary verb “Will”

How to use would and should modals