Codex (Lat), in Roman antiquity, originally the trunk of a tree, afterward applied to the wooden tablets smeared with wax which were used for writing. At a later period it became the name of all large manuscripts (codices manuscript!), as the works of the historians and poets; and under the emperors and subsequently, it designated collections of civil and ecclesiastical laws. Of the last, the oldest and most celebrated are the Codex Theodosianus, the Codex Justinianus, the Codex Canonum Ecclesiasticorum; belonging to the time of Pope Innocent I., and the Codex Canonum Ecclesice universce, revised by the monk Diony-sius about 527. Its principal modern application is to the uncial manuscripts of the New Testament, as the codices Alexandrinus, Va-ticanus, Ephraemi, Bezae or Cantabrigiemis, Claromontanus, etc, 41 in all, which are also designated by the Roman letters, as codices A, B, C, D, or by combinations, as Fa, Wb, or by the Greek letters, as A, 0. - A codex re-scriptus (Lat., a rewritten codex), now usually termed a palimpsest, is an ancient parchment on which the original writing has been defaced, and, a different composition copied.