a thin square of mounted glass used to protect a photographic slide
cover glass in American English
noun
a thin, round or square piece of glass used to cover an object mounted on a slide for microscopic observation
Also called: cover slip
Word origin
[1880–85]This word is first recorded in the period 1880–85. Other words that entered Englishat around the same time include: automatism, interface, irredentist, jackpot, pari-mutuel