Definition

1. Noun:
   • A type of auxiliary verb that is used to express modality—the speaker's attitude toward the action or state described by the main verb. It indicates concepts such as possibility, necessity, permission, ability, or obligation.

Usage

• Modal auxiliary verbs are used with the base form (infinitive without "to") of a main verb to modify its meaning.
• They do not change form (e.g., they do not add "-s" for third-person singular).
• They are followed directly by the main verb (e.g., "She can swim").
• They are used to form questions and negatives without the auxiliary "do" (e.g., "Can she swim?", "She cannot swim").

Examples

• Expressing ability: "I can speak French."
• Expressing permission: "You may leave the table."
• Expressing obligation: "You must complete the assignment."
• Expressing possibility: "It might rain tomorrow."
• Expressing future intention: "I will call you later."

Advanced Usage

• Expressing logical deduction: Modal auxiliaries can express degrees of certainty.
  • "That must be the postman." (high certainty)
  • "That could be the postman." (lower certainty)
• Expressing past modality: Some modals use perfect infinitives (have + past participle) to refer to past situations.
  • "She must have forgotten our meeting." (deduction about the past)
  • "You should have called me." (unfulfilled past obligation)

Variants and Related Words

• Modal verb: A common synonym for "modal auxiliary verb."
• Semi-modal verb: A verb that shares some characteristics with modal auxiliaries but not all (e.g., "need to," "have to," "ought to").
• Central modal verbs: The core group of single-word modals: .

Synonyms

• Modal verb
• Modal

Related Phrases and Concepts

• Modality: The grammatical category expressed by modal auxiliary verbs, encompassing notions like necessity, possibility, and permission.
• Auxiliary verb: The broader category of "helping verbs" that includes modal auxiliaries as well as primary auxiliaries (be, have, do).

Noun

1. an auxiliary verb (such as `can' or `will') that is used to express modality