- The definition of a plaintiff is someone who brings a lawsuit against someone into court.
An example of a plaintiff is a wife filing for divorce.
Origin of plaintiffMiddle English plaintif ; from Old French mournful, making complaint ; from plaindre ; from plainte: see plaint
Origin of plaintiffMiddle English plaintif, from Anglo-Norman pleintif, from Old French plaintif, aggrieved; see plaintive.
From Middle English plaintif, from Old French plaintif (“complaining; as a noun, one who complains, a plaintiff") from the verb plaindre. See plaintive.