An eyepiece is the part of a device, such as a microscope or telescope, that you look through to see things magnified or closer. It is like a small lens that helps you focus and observe objects with your eyes. Full definition
It fits right into a standard telescope eyepiece of 1 1/4 inches. (geekwrapped.com)
In my 32 mm eyepiece with a true field of view of 46 ′, the cluster and the nebulosity lie at the end of an S - shaped asterism of stars, which can be identified easily. (backyard-astro.com)
I put my 32 mm eyepiece into the diagonal and there it was! (backyard-astro.com)