a. [f. Gr. τρι-, TRI- + κύκλος circle + -IC.]

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  1.  Bot. Arranged in three whorls.

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1900.  in B. D. Jackson, Gloss. Bot. Terms.

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  2.  Chem. Of a carbon compound: Having three rings or closed chains of atoms in its structural formula; e.g., phenanthrene. (Ger. tricyklisch.).

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1891.  Jrnl. Chem. Soc., LX. 1258. The two best known tricyclic compounds, anthracene and phenanthrene.

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