Young Blonde Girl With A Book Shows Off In The Living Room At Home

The word comes from Old English "bōc" which itself comes from the Germanic root "bōk-", cognate to beech. Similarly, in Slavic languages (for example, Russian, Bulgarian) "буква" (bukva—"letter") is cognate with "beech". In Serbian, another Slavic language, the word "буквар" (bukvar) refers specifically to a primary school textbook that helps young children master the techniques of reading and writing.
It is thus conjectured that the earliest Indo-European writings may have been carved on beech wood. Similarly, the Latin word codex, meaning a book in the modern sense (bound and with separate leaves), originally meant "block of wood".