• Something that lacks definition
  Definition
  A definition is a passage that explains the meaning of a term , or a type of thing. The term to be defined is the definiendum. A term may have many different senses or meanings...
  
  
• In mathematics, something which lacks well-definition
• In calculus, an indeterminate form
  Indeterminate form
  In calculus and other branches of mathematical analysis, an indeterminate form is an algebraic expression obtained in the context of limits. Limits involving algebraic operations are often performed by replacing subexpressions by their limits; if the expression obtained after this substitution...
  
  
• Undefined citizenship, a term used sometimes for statelessness
  Statelessness
  Statelessness is a legal concept describing the lack of any nationality. It is the absence of a recognized link between an individual and any state....
  
  

In computing

• Undefined behavior of some software
• Undefined value
  Undefined value
  In computing , undefined value is a condition where an expression has not a correct value, although it is syntactically correct. Undefined value may not be confused with empty string, boolean "false" or other "empty" values...
  
  , a condition in programming
• A function or variable lacking declaration (computer programming)
• A variable lacking Initialization (programming)
  Initialization (programming)
  In computer programming, initialization is the assignment of an initial value for a data object or variable. The manner in which initialization is performed depends on programming language, as well as type, storage class, etc., of an object to be initialized. Programming constructs which perform...
  
  
• An unavailable linker symbol (function, or global variable), see dynamic linker
  Dynamic linker
  In computing, a dynamic linker is the part of an operating system that loads and links the shared libraries for an executable when it is executed. The specific operating system and executable format determine how the dynamic linker functions and how it is implemented...
  
  

See also

• Null (disambiguation)
• Void (disambiguation)
• Invalid (disambiguation)
• Definition (disambiguation)
  Definition (disambiguation)
  Generally, a definition delimits or describes the meaning of a concept or term.Definition may also refer one of the following.- Science, mathematics and computing:...
  
  
• Definable (disambiguation)
• Undefined Fantastic Object
  Undefined Fantastic Object
  is the twelfth main game of the Touhou Project scrolling shooter series. Made by the dōjin game maker Team Shanghai Alice. The full version of the game was released in the 76th Comiket on August 15, 2009 following the retail release on September 11, 2009....