undefined value
Computing term for a variable or expression that has not been assigned a defined value.
This variable remains an undefined value, so it cannot be used in calculations.
Please add handling for when an undefined value is returned.
未定義 is the state of being undefined, while 未定義値 specifically refers to the undefined value itself.
初期値 is an initial (defined) value, contrasting with 未定義値 which is not defined at all.
Compound of 未 (not yet), 定義 (definition), and 値 (value). A straightforward technical term.