from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. manganese dioxide, occurring in hard tetragonal crystals

from the GNU version of the Collaborative International Dictionary of English

  • n. Manganese dioxide, occurring in tetragonal crystals nearly as hard as quartz.

from The Century Dictionary and Cyclopedia

  • n. Anhydrous manganese dioxid (MnO2), a mineral of a light steel-gray color and hardness nearly equal to that of quartz.


Ancient Greek to become grey. (Wiktionary)


Sorry, no example sentences found.

Wordnik is becoming a not-for-profit! Read our announcement here.


Log in or sign up to get involved in the conversation. It's quick and easy.