eyeball

Short definition from Wiktionary

Noun

1. 1
   The ball of the eye.
2. 2
   A person's focus of attention.
3. 3
   Surveillance.
4. 4
   A readership or viewership.
5. 5
   A face-to-face meeting.
6. 6
   A favourite or pet; the apple of someone's eye.

Verb

1. 1
   To gauge, estimate or judge by eye, rather than measuring precisely; to look or glance at.
2. 2
   To stare at intently.
3. 3
   To roll one's eyes.