Definitions for eyepieceˈaɪˌpis
Random House Webster's College Dictionary
the lens or combination of lenses in an optical instrument through which the eye views the image formed by the objective lens or lenses; ocular.
Origin of eyepiece:
combination of lenses at the viewing end of optical instruments
The lens (or combination of lenses) at the eye end of a microscope or telescope by which the image is viewed.
the lens, or combination of lenses, at the eye end of a telescope or other optical instrument, through which the image formed by the mirror or object glass is viewed