Definition of tetracyclic in US English:



  • (of an organic compound) having four fused rings of atoms in its molecule.

    • ‘Mirtazapine is a tetracyclic antidepressant unrelated to tricyclic antidepressants and SSRIs.’
    • ‘A 1998 study showed that pentacyclic alkaloids weakly activated human B- and T-lymphocytes, and that tetracyclic oxindole alkaloids reduced the activity of pentacyclic oxindoles.’
    • ‘Cucurbitacins are oxygenated tetracyclic triterpenes that have been shown to have emetic, antineoplastic, and cytotoxic effects on herbivores, resulting in feeding and oviposition deterrence and reduced growth of consumers.’
    • ‘Practitioners prescribing the tetracyclic antibiotics should be aware of the syndrome of increased intracranial pressure, and pay particular attention to the ocular fundus for papilloedema.’
    • ‘Maprotiline is the only tetracyclic antidepressant available in the US.’


Early 20th century: from tetra- ‘four’ + Greek kuklos ‘circle’ + -ic.