pur·su·er \-süə(r), -su̇(ə)r, -su̇ə\noun (-s) Etymology: Middle English pursuere, from pursuen to pursue + -ere -er : one that pursues: as a.: one that chases or follows after < that canine pursuer of the rabbit > < a devoted pursuer of knowledge > b.obsolete: persecutor c.chiefly Scots & eccl law: plaintiff, prosecutor