Medical Definition of porphin
: a deep purple crystalline compound C20H14N4 that is made synthetically from pyrrole and formaldehyde, contains four pyrrole rings joined by =CH− groups so as to give a heterocyclic arrangement, and forms the essential skeletal structure of the porphyrins, heme, and chlorophyll
Seen and Heard
What made you want to look up porphin? Please tell us where you read or heard it (including the quote, if possible).