book-word

Noun

book word (plural book words)

1. A word that is encountered in writing but not usually in speech, which people may therefore not know how to pronounce (correctly).
   • The second, being a ‘book word,’ has quite an artificial pronunciation.1871, Alexander John Ellis, On Early English Pronunciation, with Especial Reference to Shakspere ...
2. A word that is borrowed into a vernacular from a closely related literary language, thus being etymologically related to native vocabulary, but not showing regular sound changes.
   • French loyal and légal are both from Latin lēgālis. While the former was inherited, the latter is a book word.