means A lawyer who represents the government in bringing criminal charges against an accused person and arguing the case against them in court.

from From Latin prosequi, 'to follow after, pursue,' built from pro- ('forward') and sequi ('to follow' — the same root that gives us 'sequence' and 'pursue'). A prosecutor is literally one who follows a matter through, pursuing it to its end. The word entered English by way of legal Latin, where 'to prosecute' first meant simply to carry on or pursue any undertaking, before narrowing to the courtroom sense of pursuing a charge against someone.