a book: a whole written work, in practice a rolled scroll, named as a complete volume and usually identified by its author or its contents
Every book in the New Testament world was a roll. A long strip of papyrus or prepared animal skin was written on in columns and then wound up, so a reader unrolled it to find a place and wound it back when finished. The word itself began as the name of the papyrus plant that supplied the writing surface, which is also why our word "Bible" traces back to it.
What holds the uses together is that this word points at the book as a whole rather than at any line inside it. It is the natural way to name a recognized work by its author or its subject: the book of Moses, the book of the words of Isaiah, the book of Psalms, the book of the prophets. When a writer instead has a physical roll in his hands, something to be taken, opened, sealed, or rolled shut, he normally reaches for the commoner word for a scroll (βιβλίον).
From that one core the range runs in four directions:
- a book of Scripture, quoted as the word of God and named by its author or its contents
- an ordinary book with nothing sacred about it, such as the volumes of spells that new believers in Ephesus stacked up and burned
- a written record of a person's descent, which is how Matthew's Gospel opens
- a heavenly book, God's own list of the people who belong to him
The last of these carries the most weight. Behind it stands a long biblical picture of God keeping written records: a book Moses asks to be blotted out of, a roll of remembrance kept for those who fear the Lord, books opened when the court sits in Daniel 7:10 (סְפַר). In the New Testament that book is simply called the book of life, and what decides a person's future is whether the name is written in it.