is \Is\, v. i. [AS. is; akin to G. & Goth. ist, L. est, Gr. ?, Skr. asti. [root]9. Cf. Am, Entity, Essence, Absent.] The third person singular of the substantive verb be, in the indicative mood, present tense; as, he is; he is a man. See Be.
Note: In some varieties of the Northern dialect of Old English, is was used for all persons of the singular.
For thy is I come, and eke Alain. --Chaucer.
Aye is thou merry. --Chaucer.
Note: The idiom of using the present for future events sure to happen is a relic of Old English in which the present and future had the same form; as, this year Christmas is on Friday.