0th

0th or zeroth is an ordinal for the number zero sometimes used under zero-based numbering, and can refer to:

• 0th grade, another name for kindergarten
• 0th dimension
• 0th planet, a name for Vulcan (hypothetical planet)
• 0th United States Congress, also called the Congress of the Confederation
• January 0 or January 0th, an alternate name for December 31
• The zeroth law of thermodynamics
• Zeroth-order logic
• The Zeroth Law, an addition to the Three Laws of Robotics
• Zeroth order approximation; see Orders of approximation
• Zeroth, the fastest demo or highest score on a level or episode in N (game)