Wiktionary
n. A square or circular piece of glass that covers the specimen on a microscope slide
WordNet
n. a small and very thing piece of glass used to cover the specimen on a microscope slide [syn: cover glass]
Wikipedia
A cover slip, coverslip or cover glass is a thin flat piece of transparent material, usually square or rectangular, about 20 mm (4/5 in) wide and a fraction of a millimetre thick, that is placed over objects for viewing with a microscope. The object is usually held between the cover slip and a somewhat thicker microscope slide, which rests on the microscope's stage or slide holder and provides the physical support for the object and slip.
The main function of the cover slip is to keep solid specimens pressed flat, and liquid samples shaped into a flat layer of even thickness. This is necessary because high-resolution microscopes have a very narrow region within which they focus.
The cover glass often has several other functions. It holds the specimen in place (either by the weight of the cover slip or, in the case of a wet mount, by surface tension) and protects the specimen from dust and accidental contact. It protects the microscope's objective lens from contacting the specimen and vice-versa; in oil immersion microscopy or water immersion microscopy the cover slip prevents contact between the immersion liquid and the specimen. The cover slip can be glued to the slide so as to seal off the specimen, retarding dehydration and oxidation of the specimen. Microbial and cell cultures can be grown directly on the cover slip before it is placed on the slide, and specimens may be permanently mounted on the slip instead of on the slide.
Microscopy - Protocols teaching webpage by the Moores Cancer Center, University of California at San Diego. Accessed on 2013-02-07.
Usage examples of "cover slip".
She let the cover slip, on purpose of course, and obligingly he dropped his gaze.
I then separated the ether carefully from the rest of the blood mixture and put a few drops of it on a slide, covered them with a cover slip and sealed the edges with balsam.
When I walked in, he was making a permanent slide, using a pipette to touch a drop of Cargille melt mount on the edge of a cover slip while other slides warned up on a hot plate.
He could see the paper-thin section of brain sealed with a cover slip.
Rachel carried the feather to a work counter, pulled two strands from it, placed them on a glass slide, dropped liquid onto them, poked and repositioned them with the tip of a needle, blotted, and added a cover slip.
The slide took almost no time to dry, and I dripped Nicolaou stain on it and sealed it with a cover slip.