di-

1. Two, twice. 2. In chemistry, often used in place of bis- when not likely to be confusing; e.g., dichloro- compounds. Cf.:bi-, bis-. [G. dis, two]

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prefix denoting

two or double.

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[Gr. dis twice] a prefix meaning twice. In chemical nomenclature, the use of di- is preferred to the use of bi- (q.v.).