Horizontal Posted on 15th November 20156th September 2020 by ThePD (The Project Definition) Horizontal means in parallel to the ground or to the bottom or top edge of something. (Opposite of the Vertical) 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 Technology and tagged geology, science. 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.