tricyclic

 
Pronunciation: /trʌɪˈsʌɪklɪk/

adjective

Chemistry
  • (of a compound) having three rings of atoms in its molecule.

noun

(usually tricyclics) Medicine
  • any of a class of antidepressant drugs having molecules with three fused rings.

Origin:

late 19th century: from tri- 'three' + Greek kuklos 'circle' + -ic