“2. The word xulon, which generally denotes a piece of a dead log of wood or timber, for fuel or for any other purpose. It is not like dendron, which is used of a living, or green tree, as in Matt. 21:8. Rev. 7:1, 3; 8:7; 9:4, &c. As this latter word xulon is used for the former stauros, it shows us that the meaning of each is exactly the same.”
(Companion Bible by E.W. Bullinger, appendix # 162)

Dendron is used for a living tree and is where we get the word dendronology, the study of trees, but Bullinger’s explanation is too short to do the subject justice. When xylon, or xulon, refers to the crucifixion the meaning is not exactly the same and when it is used it’s with Deut. 21:22-23 in mind. Xylon is translated in various ways including clubs (Matt. 26:47, 55), stocks (Acts 16:24) and wood (1 Cor. 3:12) but it also refers to a tree in what is probably a figurative sense (Luke 23:31). Xylon, is used for a living tree in Luke 23:31, Rev. 2:7, Rev. 22:2 and Rev. 22:14. There are some examples in the first three chapters of Genesis where xulon and xulou are translated in the LXX as ‘tree’ and ‘trees’ (xylon – 1:11, 12, 2:9 and 3:6. xulou – 2:16, 2:17, 3:1, 3:3, 3:8, 3:11, 3:12, 3:17, 3:22 and 3:24). http://www.authentic-christianity.org/gn1to4.htm

The treatment of xylon in “Jehovah’s Witnesses and the Cross” at http://forananswer.org/Top_JW/jwcross.pdf is excellent. In that paper it says….

“In pre-Republican times, the Romans sometimes punished disobedient slaves by fastening them to barren trees and scourging them to death. Occasionally the victims were forced to bear the patibulum before they were hung. This form of punishment was called arbor infelix or infelix lignum, and several later Latin writers confused it with crucifixion. As a result, the two-beamed cross became known as an arbor or lignum (both Latin words mean “tree”).”

She has researched the Latin much more than I have and this agrees with Martin Hengel who said from the third or second century BC arbor infelix was evidently interpreted as crucifixion (Crucifixion in the Ancient World and the Folly of the Message of the Cross, p. 39). But isn’t it possible that arbor infelix and infelix lignum took on a new meaning over time? In Rome crucifixion originally was used for slaves (servile supplicium – slaves punishment) and the slave was scourged on a tree. Either way the words in Latin that meant tree were used to describe a two beam cross. Surprisingly the Vulgate translates ‘ets as ‘patibulo’ in Deut. 21:22 instead of arbor or lignum and is translated as ‘ligno’ in verse 23. This may have been because of the similarity to Roman crucifixion to that passage. Ligno, in various forms, corresponds to xylon in Revelation and ‘ets is a Hebrew word for tree but the word in Ezra 6:11 is ‘a (beam).

Here are some other points about xylon in Jehovah’s Witnesses and the Cross:

1) ξυλον (xulon) became an acceptable synonym for σταυρος (stauros) by many Greek-speaking Jews and Christians.

2) Paul’s discourse in Acts 13:28-30 may be a midrash on Deuteronomy 21:22-23.

3) The Dead Sea Scrolls twice cited Deuteronomy 21:22-23 with reference to crucifixion. (11QT, column 64, lines 6-13; 4QpNah, fragments 3-4, column 1, lines 1-11.)

4) The Jewish perception of Roman crucifixion revolved around Deuteronomy 21:22-23.

My comments: The whole discussion about the usage of xylon in reference to Jesus’ crucifixion should be based on Deuteronomy 21:22-23. There are a few things that are noteworthy. First, xulon is only used for Jesus’ crucifixion five times in the N.T. – Acts 5:30, 10:39, Acts 13:29, Galatians 3:13 and 1 Peter 2:24. The manner on which Jesus was killed on the xylon is described in only three of them. The word stauroo (crucify) isn’t used to describe how Jesus was killed on the ξυλον. The word used is kremannymi which means hang, hanged or hanging. Deuteronomy 21:22-23 is plainly spelled out in two of the five verses – Gal. 3:13 and 1 Pet. 2:24.

Each of the five verses occur after the crucifixion and none are in the gospel accounts. They were all written looking back at Jesus’ death and resurrection and Peter and Paul saw how Deut. 21:22-23 foreshadowed Jesus’ death even though it was orignally a command for someone who had been killed for committing a capital offense. When the Romans took control of Judea and brought with them crucifixion they would usually leave bodies on crosses and stakes after the condemned person died. Add to that the fact the condemned had been killed on a tall wooden object Deut. 21:22-23 naturally would have come to the mind of Jewish people. The differences between Christ and those to whom that command applied is Jesus was innocent of his charges and he was alive when nailed to the cross. Its original application was for the guilty but was applied to an innocent man who had to become a curse for us; the righteous for the unrighteous (1 Pet. 3:18).

Kremannymi is in another verse about the crucifixion in the book of Luke. He didn’t mention stauros or xylon but it is still significant:

One of the criminals who hung there hurled insults at him: “Aren’t you the Christ? Save yourself and us!” But the other criminal rebuked him. “Don’t you fear God,” he said, “since you are under the same sentence? We are punished justly, for we are getting what our deeds deserve. But this man has done nothing wrong.” Luke 23:39-41

The guilt of the two thieves is contrasted with Jesus’ innocence similarly to Gal 3:13 and 1 Pet. 2:24. In Luke 23:39 and the five verses that speak of Jesus dying on a xylon one of two things comes out:

Christ was innocent and didn’t deserve capital punishment as did those whose bodies were hung on a tree in the O.T.

Jesus became a curse for use when he was crucified.

In fact, “Xulon” is used in all three synoptics to refer to the staves that those who arrested Jesus were carrying (they weren’t carrying trees). It refers in Acts 16 to the stocks that Paul and Silas were locked in in the Philippian jail (they weren’t locked in trees). So it seems that “Xulon” was also used to refer broadly to things made out of wood as well as to actual trees.