Officially, the noun whereabouts can be treated as singular or plural, but it's more common to use it as plural. News stories about escaped prisoners or criminals on the run often mention that their whereabouts are unknown, and parents who like to keep tabs on a teenager's whereabouts sometimes buy her a cell phone. The earliest use of whereabouts, one sometimes used today, was as an interrogative adverb: "Whereabouts will you be this afternoon?"