Pertaining to the law or rule of law, legal; judicial, related to the administration of justice (as to jurisprudence, or to the function of a judge or court).
Acceptable, proper or correct; in accordance with the rules.
Well grounded or justifiable, pertinent.
Of an argument: whose conclusion is always true whenever its premises are true.
Genuine - as distinguished from efficient or regular - sacrament.
Related to the current topic, or presented within context, relevant.
Of a formula or system: such that it evaluates to true regardless of the input values.