'IS' definitions:

Definition of 'Is'

From: GCIDE

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. [1913 Webster]
Note: In some varieties of the Northern dialect of Old English, is was used for all persons of the singular. [1913 Webster]
For thy is I come, and eke Alain. --Chaucer. [1913 Webster]
Aye is thou merry. --Chaucer. [1913 Webster]
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. [1913 Webster]
To-morrow is the new moon. --1 Sam. xx. 5. Isabel