means The criminal act of deliberately lying under oath after swearing to tell the truth, typically in court or a sworn statement.

from From Latin 'periurium,' a false oath, built from 'per-' (here meaning 'to the detriment of,' a twisting or breaking) plus 'iurare,' to swear — the same 'iurare' that gives us 'jury,' 'just,' and 'justice.' So baked into the word is the idea of an oath gone wrong: you don't just lie, you lie across or against your own sworn word. It reached English through Old French 'parjurie,' carrying the sense of a vow shattered the moment it left your lips.