Definify.com
Webster 1913 Edition
Expanse
Ex-panse′
,Noun.
 That which is expanded or spread out; a wide extent of space or body; especially, the arch of the sky. 
“The green expanse.” Savage.
 Lights . . . high in the 
expanse 
of heaven. Milton.
The smooth 
 expanse 
of crystal lakes. Pope.
Ex-panse′
,Verb.
 T.
 To expand. 
[Obs.] 
That lies 
expansed 
unto the eyes of all. Sir. T. Browne.
Webster 1828 Edition
Expanse
EXPANSE
,Noun.
  The smooth expanse of crystal lakes.