In a general sense, to argue in support of a claim, or in defense against the claim of another.

In law, to present an answer to the declaration of a plaintiff; to deny the plaintiffs declaration and demand, or to allege facts which show that he ought not to recover in the suit. The plaintiff declares or alleges; the defendant pleads to his declaration. The king or the state prosecutes an offender, and the offender pleads not guilty, or confesses the charge.

To urge reasons for or against; to attempt to persuade one by argument or supplication; as, to plead for the life of a criminal; to plead in his favor; to plead with a judge or with a father. O that one might plead for a man with God, as a man pleadeth for his neighbor! Job 16:21.

To supplicate with earnestness.

To urge; to press by operating on the passions. Since you can love, and yet your error see, The same resistless power may plead for me.

To discuss, defend and attempt to maintain by arguments or reasons offered to the tribunal or person who has the power of determining; as, to plead a cause before a court or jury. In this sense, argue is more generally used by lawyers.

To allege or adduce in proof, support or vindication. The law of nations may be pleaded in favor of the rights’ of embassadors.

To offer in excuse. I will neither plead my age nor sickness in excuse of faults.

To allege and offer in a legal plea or defense, or for repelling a demand in law; as, to plead usury; to plead a statute of limitations.

In Scripture, to plead the cause of the righteous, as God, is to avenge or vindicate them against enemies, or to redress their grievances. Isaiah 51:22.