The Greek word used is starius from the base of G2476 a stake or a post can you nail him on a concrete nail stake the Bible says he was nailled to a wooden cross he was nailed to a tree ways of defining it,It was a tree, it was a cross it his not only JESUS that was nailed he was nailed with two other people the thieves they were three of them at Golgotha going to history not all cross has a cross in it,It can be a tree,post or stake.