The Hebrew word tsela is the word translated in Genesis 2 as "rib". The word tsela is never used after Genesis 2 to describe any part of the human body at all. It is used, instead, in many places (with the majority being found in Exodus) to describe the "sides" of things. It is also translated in other places as corners, boards and chambers. A complete list of the uses of tsela can be found in the link to the word. What is notably absent is any usage in the Bible of the word as "an 'appendage' jutting out from a central structure". It isn't that it can't be seen as an "appendage" -- it is the "jutting out" part of the description that I find problematic.
Ziony Zevit, distinguished professor of Biblical Literature and Northwest Semitic Languages at the American Jewish University in California, argues the Biblical story has been wrongly interpreted since a mistranslation confused rib with baculum, or penis bone.
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“This Hebrew word occurs some 40 times in the Hebrew Bible, where it refers to the side of a building or of an altar or ark, a side-chamber, or a branch of a mountain. In each of these instances, it refers to something off-center, lateral to a main structure,” Zevit wrote.
Tsela was first translated as rib in the Septuagint, a Greek translation of the Hebrew Bible dating to the mid-third century B.C.
It would have then lost its original meaning, which according to Zevit relates to “limbs lateral to the vertical axis of an erect human body: hands, feet, or, in the case of males, the penis.”
“Of these appendages, the only one lacking a bone is the penis,” Zevit wrote.