'Welkin' definitions:

Definition of 'welkin'

noun

The apparent surface of the imaginary sphere on which celestial bodies appear to be projected [syn: celestial sphere, sphere, empyrean, firmament, heavens, vault of heaven, welkin]

From: GCIDE

Welkin \Wel"kin\, n. [OE. welken, welkene, welkne, wolcne, weolcne, AS. wolcen, pl. wolcnu, a cloud; akin to D. wolk, OFries. wolken, OS. wolkan, G. wolke, OHG. wolchan, and probably to G. welk withered, OHG. welc moist, Russ. & OSlav. vlaga moisture, Lith. vilgyti to moisten.] The visible regions of the air; the vault of heaven; the sky. [1913 Webster]
On the welkne shoon the sterres lyght. --Chaucer. [1913 Webster]
The fair welkin foully overcast. --Spenser. [1913 Webster]
When storms the welkin rend. --Wordsworth. [1913 Webster]
Note: Used adjectively by Shakespeare in the phase, "Your welkin eye," with uncertain meaning. [1913 Webster]