I. | ̷ ̷ ̷ ̷ ̷ ̷|sīklik, -lēk also -sik- adjective
Etymology: International Scientific Vocabulary heter- + cyclic
: relating to, characterized by, or being a ring composed of atoms of different elements
furan and quinoline are heterocyclic
— distinguished from isocyclic
II. noun
: a heterocyclic compound or a heterocylic ring system