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tet·ra·pyr·role also tet·ra·pyr·rol .te-trə-'pi(ə)r-.ōl n a chemical group consisting of four pyrrole rings joined either in a straight chain (as in phycobilins) or in a ring (as in chlorophyll)
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tet·ra·pyr·role (tet″rə-pə-rōlґ) a compound containing four pyrrole rings, e.g., heme or chlorophyll.Medical dictionary. 2011.