the word subpoena is a direct borrowing from the latin phrase "sub poena," which literally means "under penalty." this phrase was the opening of a medieval writ commanding a person to appear in court or face a penalty. the term entered middle english in the late 15th century as a noun for this specific legal document. over time, it also became established as a verb for the act of issuing such an order. the modern meaning retains the core concept of a compulsory command, where the implied penalty for non-compliance is a legal sanction.

Structure: sub (under) + poena (penalty) sub (latin, prefix meaning "under"); poena (latin, noun meaning "penalty, punishment")