jur/jus

law; swear an oath

Spelled jur, jus, jud · Latin jus (stem jur-) 'law, right'; jurare 'swear an oath'

Romans swore by jurare: a juror swears an oath, perjury breaks one, and abjuring means swearing something away.

Words built from it

abjure — Formally give up a belief, claim, or practice.
Latin ab- (away) + jurare (swear) → abjurare (deny on oath) → abjure
perjury — The act of deliberately lying under oath.
Latin per- (wrongly) + jurare (swear) → perjurium (false oath) → perjury
adjudicate — Make a formal judgment about a dispute.
Latin ad- (to) + judicare (judge), from judex (judge: jus, law + dicere, declare) → adjudicare → adjudicate
jurisdiction — The legal authority to make decisions, or the area that authority covers.
Latin juris (of law) + dictio (declaring), from dicere (say) → jurisdictio → jurisdiction
justice — Fair treatment and the proper application of law.
Latin jus (law, right) → justus (lawful, fair) → justitia (fairness) → Old French justice → justice
juror — A member of a jury who has sworn to consider a case fairly.
Latin jurare (swear) → Anglo-French jurour (one who swears) → juror
conjure — Call something forth, especially by magic or imagination.
Latin con- (together) + jurare (swear) → conjurare (swear together; invoke solemnly) → Old French conjurer → conjure

Jurassic — Contains jur, but names the Jura Mountains, where rock of that period was first described; nothing to do with Latin jus, juris (law).