tricyclic

Having or being a molecular structure that contains three closed rings.

A tricyclic antidepressant drug.

In chem., consisting of three rings or closed chains of atoms (usually o. carbon) united together, with any other atoms united to those of such rings. See tricyclic system.

Having three rings of atoms in the molecule.

an antidepressant drug that acts by blocking the reuptake of norepinephrine and serotonin and thus making more of those substances available to act on receptors in the brain