of, for, or constituting punishment, esp. legal punishment
specifying or prescribing punishment: a penal code
making a person liable to punishment: a penal offense
Origin:
ME < L poenalis < poena, punishment (> pain) < Gr poinē, penalty, fine < IE *kwoina, punishment < base *kwei-, to heed, respect, avenge > Sans cáyatē, (he) avenges, Lith káina, price