tri|cy|clic «try SY klihk, -SIHK lihk», adjective, noun.
–adj.
1. passing through or having three cycles.
2. Chemistry. containing three rings of atoms in the molecule.
–n.
any one of a class of tricyclic compounds used as drugs to relieve depression: »
Tricyclics…help the people who get to sleep, but wake up at about three, seeing everything as a disaster (Listener).
Useful english dictionary. 2012.