Origin: Latin prefix sub-
Subpoena has 4 different meanings across 2 categories:
a writ issued by court authority to compel the attendance of a witness at a judicial proceeding; disobedience may be punishable as a contempt of court
"The judge signed a subpoena ordering my neighbor to appear in court next Tuesday or face arrest for contempt."
A writ requiring a defendant to appear in court to answer a plaintiff's claim.
"The judge issued a subpoena compelling the witness to appear in court to testify about the accident that sparked the lawsuit."
To summon with a subpoena.
"The lawyer received a formal notice to appear in court, which is known as being summoned with a subpoena."
The word comes from the Latin phrase sub pena, meaning "under penalty," which referred to a legal order requiring someone to appear in court or face punishment. The modern verb form developed later from this original noun.