Definition of eyeballs:
(n) :
The ball of the eye.
(v) :
(transitive, informal) To gauge, estimate or judge by eye, rather than measuring precisely; to look or glance at.
(v) :
(transitive, informal) To stare at intently.
(n) :
An instance of eyeballing something.
(n) :
(informal) Surveillance.
(n) :
(marketing, in the plural) A readership or viewership.