This term is commonly used when referring to a person whose location is unknown, often due to circumstances such as an accident or disaster.

This meaning is used more generally and can refer to someone who has simply lost their way, not always implying a serious situation.

This phrase is often used in emergency situations or reports, suggesting that a person has not been found despite efforts to locate them.

This phrase indicates that it is not known where someone is located, typically used in formal or legal contexts.