A stake or a pole.
You have a misunderstanding somewhere, because it is correct.
There is a user here at Y/A's that is an Author and a reader of Koine & Coptic Greek,
he is not a Jehovah's Witness, and he says, and explains that it is correct....
A stake, an upright pole.
Did Jesus Really Die on a Cross?
http://www.watchtower.org/e/200604a/article_01.htm
Long before the Christian era, crosses were used by the ancient Babylonians
as symbols in their worship of the fertility god Tammuz.
The use of the cross spread into Egypt, India, Syria, and China.
Then, centuries later, the Israelites adulterated their worship of Jehovah
with acts of veneration to the false god Tammuz.
The Bible refers to this form of worship as a ‘detestable thing.’—Ezekiel 8:13, 14.
The Gospel accounts of Matthew, Mark, Luke, and John use the Greek word stau·ros′
when referring to the instrument of execution on which Jesus died.
(Matthew 27:40; Mark 15:30; Luke 23:26)
The word stau·ros′ refers to an upright pole, stake, or post.
The book The Non-Christian Cross, by J. D. Parsons, explains:
“There is not a single sentence in any of the numerous writings forming the New Testament,
which, in the original Greek, bears even indirect evidence to the effect that the stauros
used in the case of Jesus was other than an ordinary stauros; much less to the effect that it consisted, not of one piece of timber, but of two pieces nailed together in the form of a cross.”