Available Definitions:
1) a. - Of or pertaining to punishment, to penalties, or to crimes and offenses; pertaining to criminal jurisprudence
2) a. - Enacting or threatening punishment; as, a penal statue; the penal code.
3) a. - Incurring punishment; subject to a penalty; as, a penalact of offense.
4) a. - Inflicted as punishment; used as a means of punishment; as, a penal colony or settlement.