The term crux simplex was used by Justus Lipsius (1547–1606) to indicate a plain transom-less wooden stake used for executing either by affixing the victim to it or by impaling him with it (Simplex [...] voco, cum in uno simplicique ligno fit affixio, aut infixio). He thus distinguished two types of crux simplex: the crux simplex ad affixionem and the crux simplex ad infixionem.
Lipsius contrasted the crux simplex (both variations) with the two-timber structure that he called a crux compacta (Compacta Crux est, quae manu facta, idque e duplici ligno), and that he subdivided into three types: crux decussata (X-shaped), crux commissa (T-shaped) and crux immissa (†-shaped).