\Ox"ide\, n. [F. oxyg[`e]ne oxygen + acide acid: cf. F.
oxyde. The French word was correctly spelt oxide, till about
the year 1840, when, in ignorance or forgetfulness of the
true history and composition of the word, the orthography was
change to make it represent the [upsilon] of Gr. 'oxy`s, from
which it was supposed to be directly derived.] (Chem.)
A binary compound of oxygen with an atom or radical, or a
compound which is regarded as binary; as, iron oxide, ethyl
oxide, nitrogen oxide, etc.
Note: In the chemical nomenclature adopted by Guyton de
      Morveau, Lavoisier,and their associates, the term
      oxides was made to include all compounds of oxygen
      which had no acid (F. acide) properties, as contrasted
      with the acids, all of which were at that time supposed
      to contain oxygen. The orthography oxyde, oxyd, etc.,
      was afterwards introduced in ignorance or disregard of
      the true etymology, but these forms are now obsolete in
      English. The spelling oxid is not common.