adj.未阐明的，未限定的

The function returned undefined when called with that input.
这个函数在用那个输入调用时返回了未定义。
She gave an undefined answer to the question, leaving everyone confused.
她对问题给出了一个模棱两可的答案，让每个人都感到困惑。
In JavaScript, variables declared without a value default to undefined.
在JavaScript中，没有赋值的变量默认为未定义。
His mood was undefined, making it hard to predict his reaction.
他的情绪无法确定，让人难以预料他的反应。
The variable 'result' is currently undefined, so you cannot access its properties.
变量'result'当前未定义，因此你不能访问它的属性。
An undefined term in a dictionary indicates that the word has not been included yet.
字典中的未知术语表示该词尚未被收录。
The function's return type is undefined, meaning it can return any data type.
函数的返回类型是未定义的，意味着它可以返回任何数据类型。
The parameter 'username' is undefined, please check your input.
参数'username'未定义，请检查你的输入。
Her future plans were somewhat undefined, as she hadn't made any concrete decisions yet.
她的未来计划有些模糊，因为她还没有做出任何明确的决定。
In mathematics, an undefined operation, like dividing by zero, leads to an undefined result.
在数学中，像零除以这样的未定义操作会导致未定义的结果。