modal verb
Definition - An auxiliary verb that expresses possibility, probability, desire, and constraint, e.g. can, may, might, could, must, and ought.

Example -
He might go home.

Etymology -
The term derives from the Latin modus, measure or manner or mode

Oxford English Dictionary -
Its first citation is from 1798:
"Our language has made but small progress compared either with the Greek or with the Latin … even in this Modal and Temporal abbreviation."
(Tooke Purley ii. (1805) 467)

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