Juror
late Middle English: from Old French jureor, from Latin jurator, from jurare ‘swear’, from jus, jur- ‘law’.
wiktionary
From Middle English jurour, jurrour, borrowed from Anglo-Norman jurour and Old French jureor, from the verb jurer(“to swear”), or possibly from Latin iūrātor, iūrātōrem [1].
etymonline
juror (n.)
"one who serves on a jury," c. 1300 (late 12c. in Anglo-Latin), from Anglo-French jurour (late 13c.), Old French jureor "character witness, person who swears an oath," from Latin iuratorem (nominative iurator) "swearer, sworn census-clerk," agent noun from iurare "to swear," from ius (genitive iuris) "law" (see jurist). Meaning "one of a group selected to award prizes, etc. at a public exhibition" is from 1851; this particular use seems to have arisen with the great Industrial Exhibition held that year at the Crystal Palace in London.
