secobarbital /ˌsɛk.oʊˈbɑɹ.bəˌtɔl/ noun1 •A barbiturate C₁₂H₁₈N₂O₃ that is used chiefly in the form of its bitter hygroscopic sodium salt as a hypnotic and sedative.Seconal is the commercial name of the barbiturate quinalbarbitone. Its generic name is secobarbital. — 2001 formssecobarbitals