The instrument of Jesus' crucifixion (known in Latin as crux, in Greek as stauros) is generally taken to have been composed of an upright wooden beam to which was added a transom, thus forming a "cruciform" or T-shaped structure.
Most Christian denominations present the Christian cross in this form, and the tradition of the T-shape can be traced to early Christianity and the Church fathers. Nonetheless, some late-19th century scholars maintained that it was a simple stake (crux simplex). In 2011 Gunnar Samuelsson concluded that there is not enough evidence in pre-Christian ancient texts or in the New Testament writings themselves to resolve the ambiguity of the terms referring to the instrument on which Jesus was executed. On the other hand David W Chapman argues that to take one single greek word and conclude that it has one universal and unchanging meaning like the word stauros “is a common word study fallacy in some populist literature. In fact, such terminology often referred in antiquity to cross-shaped crucifixion devices. For example, Lucian, in a brief dialogue that employs most Greek crucifixion vocabulary, refers to the "crucifixion" of Prometheus, whose arms are pinned while stretched from one rock to another. Such a cross-shaped crucifixion position in the Roman era may actually have been the norm.”
Presence or absence of crossbar
Ambiguity of terms used
The Koine Greek terms used in the New Testament of the structure on which Jesus died are stauros (σταυρός) and xylon (ξύλον). Those words, which can refer to many different things, do not indicate the precise shape of the structure. Scholars have long known that the Greek word stauros and the Latin word did not uniquely mean a cross. They have known too that the words had that meaning also, and so have not considered necessarily incorrect the traditional picture of a cross with transom.
The ambiguity of the terms was noted by Justus Lipsius in his De Cruce (1594), Jacob Gretser in his De Cruce Christi (1598) and Thomas Godwyn in his Moses and Aaron (1662).
John Pearson, Bishop of Chester (c. 1660) wrote in his commentary on the Apostles' Creed that the Greek word stauros originally signified "a straight standing Stake, Pale, or Palisador", but that, "when other transverse or prominent parts were added in a perfect Cross, it retained still the Original Name", and he declared: "The Form then of the Cross on which our Saviour suffered was not a simple, but a compounded, Figure, according to the Custom of the Romans, by whose Procurator he was condemned to die. In which there was not only a straight and erected piece of Wood fixed in the Earth, but also a transverse Beam fastened unto that towards the top thereof".
Justus Lipsius invented a specific terminology to distinguish different forms of what could be called a cross or crux. His basic twofold distinction was between the crux simplex (a simple stake) and the crux compacta (a composite of two pieces of wood). The victim could be affixed to the crux simplex or could be impaled on it. Lipsius then subdivided the crux compacta into three types: the crux decussata (X-shaped), crux commissa (T-shaped) and crux immissa (†-shaped).
Lipsius himself, as also Gretser and Godwyn, held that Jesus was nailed not to a crux simplex, but to a crux immissa. However, W. E. Vine and E. W. Bullinger, as well as Henry Dana Ward, considered that the "cross" (Greek stauros, in its original sense literally an upright pale or stake) had no crossbar, and that the traditional picture of Jesus on a cross with a crossbar was incorrect.
"Stauros" interpreted as simple stake only
In his 1871 study of the history of the cross, Episcopal preacher Henry Dana Ward accepted as the only form of the gibbet on which Jesus died "a pale, a strong stake, a wooden post".