Penta- (?), pref. [Gr. penta-, a later combining form of pente five. See Five.] 1. A combining form denoting five; as, pentacapsular; pentagon.
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2. (Chem.) Denoting the degree of five, either as regards quality, property, or composition; as, pentasulphide, containing five sulfur atoms; pentoxide, containing five oxygen atoms, etc. Also used adjectively.
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