A plaintiff is the person or group who starts a lawsuit in court, claiming that someone else has done them wrong.
From Old French 'pleintif' meaning 'complaining', from 'plaint' meaning 'lament, complaint'. It originally described someone who was sorrowful or complaining.
The plaintiff is literally the 'complainer' in the legal story—the one saying, 'Something wrong happened to me.' Once you see that, words like 'complaint' and 'plaintive' suddenly sound like family members.
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