An eye-piece is an essential part of a microscope or telescope, providing the user with a close-up view of the object under observation. Some synonyms for the word "eye-piece" include ocular, eyepiece lens, ocular lens, viewer, and viewer lens. These terms can be used interchangeably, depending on the context in which they are used. The eyepiece is a crucial component in many optical instruments, allowing the viewer to zoom in and observe the details of what is being viewed. The term "ocular" is often used to describe the eyepiece because it is the closest part of the microscope or telescope to the eye.