As a noun undersky
is the lower region of the sky.
As a verb undersay is
(obsolete) to say by way of derogation or contradiction.
undersky
English
Noun
(
underskies)
The lower region of the sky.
- Floating about the undersky — Alfred Tennyson.
undersay
English
Verb
(obsolete) To say by way of derogation or contradiction.
- (Spenser)
(
Webster 1913)