what does the prefix di- mean
Di-. a prefix, signifying twofold, double, twice. Di-. denoting two atoms, radicals, groups, or equivalents, as the case may be. See Bi-, 2. Di-. a prefix denoting through; also, between, apart, asunder, across. Before a vowel dia-becomes di-; as, diactinic; dielectric, etc. Origin: [Gr. di`s-twice; akin to two, L. bis twice. See Two, and cf. Bi-, Dia-.