|pi(ˌ)rō+ noun
Etymology: International Scientific Vocabulary pyrrh- + porphyrin
: a dark red crystalline pigment C 32 H 36 N 4 O 2 with a violet metallic luster that is the lower homologue of phylloporphyrin and that differs from most porphyrins in being a hepta-substituted derivative of porphin rather than an octa-substituted one