A lens or other optical component in an optical instrument. The telescope's optic was carefully cleaned to ensure a clear view of the stars.
The eye, especially in terms of its function as an organ of sight. The doctor examined the patient's optic to check for any signs of damage.
A device fitted to an inverted bottle for dispensing exact measures of spirits, especially in British pubs. The barman replaced the empty gin optic behind the bar.
An optical sighting device fitted to a firearm, such as a rifle scope or red-dot sight. He mounted a new optic on his rifle before the competition.