The phrase is from the Latin habeās, 2nd person singular present subjunctive active of habēre, "to have", "to hold"; and corpus, accusative singular of corpus, "body". In reference to more than one person, the phrase is habeas corpora.
Literally, the phrase means "[we command] that you should have the [detainee's] body [brought to court]"; that is, that the detainee be brought to court in person.
