Plaintiff Posted on 13th December 201513th May 2021 by ThePD (The Project Definition) A Plaintiff is 1) a person who commences an action or law suit; 2) someone who makes a legal complaint against someone else in court. Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in General and tagged legal. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.