di-

di- ¹

pref.

1. Two; twice; double: dichromatic.

2. Containing two atoms, radicals, or groups: dichloride.

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[Greek; see dwo- in Indo-European roots.]

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di- ²

pref.

Variant of dia-.

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di-¹

prefix

1. twice; two; double dicotyledon

2. (Chemistry)

a.  containing two specified atoms or groups of atoms dimethyl ether carbon dioxide

b.  a nontechnical equivalent of bi-¹ [5c]

[via Latin from Greek, from dis twice, double, related to duo two. Compare bi-¹]

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di-²

combining form

variant of dia- before a vowel diopter

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di-

A prefix that means "two," "twice," or "double." It is used commonly in chemistry, as in dioxide, a compound having two oxygen atoms.