peroxide
2. any of a class of metallic oxides, such as sodium peroxide, Na2O2, that contain the divalent ion --O-O--
3. any of certain dioxides, such as manganese peroxide, MnO2, that resemble peroxides in their formula but do not contain the --O-O-- ion
4. any of a class of organic compounds whose molecules contain two oxygen atoms bound together. They tend to be explosive
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
Peroxide
any of a class of compounds in which atoms of oxygen are bonded to each other as well as to atoms of a more electropositive element. Examples are hydrogen peroxide (H—O—O—H) and barium peroxide

The term “peroxide” was adopted by the international chemical nomenclature; in the Russian nomenclature the word for peroxide is perekis’.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.