Bacterium Posted on 3rd November 201522nd October 2020 by ThePD (The Project Definition) A Bacterium is a group of very small organism that often cause disease. (Plural Bacteria) 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 Substance and tagged bio, health. 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.