Undefined may refer to:

Mathematics[edit]

• Undefined (mathematics), with several related meanings
  • Indeterminate form, in calculus

Computing[edit]

• Undefined behavior, computer code whose behavior is not specified under certain conditions
• Undefined value, a condition where an expression does not have a correct value
• Undefined variable
• Undefined, a function or variable lacking a declaration
• Undefined, a variable lacking initialization
• Undefined, an unavailable linker symbol (function, or global variable)

Other uses[edit]

• Undefined, something that lacks any definition
• Undefined citizenship, a post-Soviet form of statelessness in Estonia

See also[edit]

• Null (disambiguation)
• Void (disambiguation)
• Invalid (disambiguation)
• Definition (disambiguation)
• Definable (disambiguation)
• All pages with titles beginning with Undefined