Book (n.) - Clay, Wax, Wood, Paper, Binary
A fairly long document usually recorded in text but sometimes containing images or audio.
It can also refer to stack of paper bound together along one side, usually with a cover made of a heavier material.
History & Etymology
In the beginning there was clay. Clay tablets used by the Sumerians to record cuneiform text. Soft clay made it easy to make imprints with a stylus, and the writing could be erased simply. When the clay was baked it created a far more permanent method for recording text.
As technology progressed the Greeks began using wooden tablets coated in wax as a temporary writing surface, because it could be erased easy and didn’t weigh nearly as much as the clay tablets.
Centuries later the Vikings after adopting an alphabet from the Romans, adapted their alphabet in such a way that made it easy to carve in to rough hewn wood. We call this style of letters runes. Now, much has been said about the magical attributes of these characters, but their main use was much more mundane. They were used for labeling items and sending short messages back and forth to one another.
Runes were used to carve short messages in to wood. Usually planks that could be used for labeling or messages. Once the message was read or no longer needed it could be shaved and the plank could be used again for a new message. These were called runesticks.
Throughout the the germanic and norse world the word for wood was something similar to bokā-. Interestingly enough that’s the origin of the words beech, oak, buckwheat. If you go far enough back the PIE word was bhego-.
So as time went on anything that was used for recording runes or text was called things like bōk in Old Frisian and Old Saxon, buok in Old Dutch, and in many other germanic languages. Even in the Gothic language bōka referred to letters of the alphabet.
That’s where we get the word book in english.