1 [no object] : to ask for something in a serious and emotional way
He begged and pleaded, but she would not change her mind.
— often + for
She pleaded [=begged] for forgiveness and got her job back.
pleading for help/mercy
— often + with
He pleaded with the judge not to send him to jail.
2 [+ object] : to try to prove (a case) in a court of law
She couldn't afford a lawyer to plead her case.
3 [no object] : to say in court that you are either guilty or not guilty of a crime : to make a plea
“How do you plead?” asked the judge.
“We plead guilty, Your Honor.”
He pled not guilty by reason of insanity. [=he said in court that he was not responsible for the crime because he was insane]
He agreed to plead to a lesser charge of manslaughter.
4 [+ object] : to give (something) as a reason or excuse for something
He pleaded that he didn't have enough money to pay his bill.
On that particular issue, I will have to plead ignorance. [=to say that I do not know anything about it]
5 : to argue in support of (a cause)
They went to plead their cause to the governor.
We will plead on your behalf.