---
title: "BIP39 Word #205: book — Seed Phrase Mnemonic Word"
url: "https://bip39-phrase.com/bip39-word/book/"
language: "en"
updated: "2026-10-19T00:00:00+00:00"
---

Word #205 00011001100 

# book — BIP39 word #205

"**book**" is word #205 of the 2048 words in the official BIP39 English wordlist, between [bonus](/bip39-word/bonus/) and [boost](/bip39-word/boost/). In a seed phrase it stands for the 11-bit value `00011001100`, decimal index 204\. 

/bʊk/  · _noun:_ a set of printed pages bound together inside a cover 

[Russian](/ru/ "The BIP39 wordlist with Russian translations"): книга 

## Binary Representation

Four 1-bits and seven 0-bits; 330 of the 2048 indexes have exactly four 1-bits.

One wrong bit turns it into (leftmost bit first):

[office](/bip39-word/office/)[flower](/bip39-word/flower/)[define](/bip39-word/define/)[another](/bip39-word/another/)[bag](/bip39-word/bag/)[budget](/bip39-word/budget/)[breeze](/bip39-word/breeze/)[blush](/bip39-word/blush/)[boil](/bip39-word/boil/)[border](/bip39-word/border/)[boost](/bip39-word/boost/) 

Position

Hex Index

0x0CC

4-Letter Prefix

book

## About "book" in BIP39

- It takes all four letters to identify "book": **"boo"** also begins [boost](/bip39-word/boost/).
- "book" appears in one of the 24 official English [test vectors](https://github.com/trezor/python-mnemonic/blob/master/vectors.json) of BIP39: vector #15 (word 12 of 24). Every official vector passes the [checksum checker](/bip39-checksum-checker/), and [How BIP39 works](/how-bip39-works/) shows how the entropy turns into such words.

Official test vector #15

[hamster](/bip39-word/hamster/) [diagram](/bip39-word/diagram/) [private](/bip39-word/private/) [dutch](/bip39-word/dutch/) [cause](/bip39-word/cause/) [delay](/bip39-word/delay/) [private](/bip39-word/private/) [meat](/bip39-word/meat/) [slide](/bip39-word/slide/) [toddler](/bip39-word/toddler/) [razor](/bip39-word/razor/) book [happy](/bip39-word/happy/) [fancy](/bip39-word/fancy/) [gospel](/bip39-word/gospel/) [tennis](/bip39-word/tennis/) [maple](/bip39-word/maple/) [dilemma](/bip39-word/dilemma/) [loan](/bip39-word/loan/) [word](/bip39-word/word/) [shrug](/bip39-word/shrug/) [inflict](/bip39-word/inflict/) [delay](/bip39-word/delay/) [length](/bip39-word/length/) 

## Word #205 in the Other 9 BIP39 Wordlists

[Czech](/czech/) cukr 

[French](/french/) banquier 

[Italian](/italian/) baritono 

[Japanese](/japanese/) うわさ 

[Korean](/korean/) 국제 

[Portuguese](/portuguese/) atingir 

[Spanish](/spanish/) azafrán 

[Traditional Chinese](/chinese-traditional/) 設 

[Simplified Chinese](/chinese-simplified/) 设 

## Similar Words — Check Carefully During Recovery

 One BIP39 word differs from "book" by just a single letter — the most common source of typos when a seed phrase is entered by hand: 

[cook](/bip39-word/cook/) 

Read aloud, "book" /bʊk/ is one sound away from this word: 

[bike /baɪk/](/bip39-word/bike/) 

Words sharing the first three letters "boo":

[boost](/bip39-word/boost/) 

## More BIP39 Words Starting with "B"

[ #201 boil ](/bip39-word/boil/)[ #202 bomb ](/bip39-word/bomb/)[ #203 bone ](/bip39-word/bone/)[ #204 bonus ](/bip39-word/bonus/)[ #206 boost ](/bip39-word/boost/)[ #207 border ](/bip39-word/border/)[ #208 boring ](/bip39-word/boring/)[ #209 borrow ](/bip39-word/borrow/) 

[View all words starting with "B" ](/bip39-words/b/) 

## Seed phrase, key and recovery guides

- [BIP 157 Client-Side Block Filtering: Compact Filters Explained](/bip-157-client-side-block-filtering/)
- [Bitcoin Core Seed Phrase: Why There Is None and How to Back Up](/bitcoin-core-seed-phrase-backup-guide/)
- [BIP38 Encrypted Private Keys: 6P Format and How to Decrypt](/bip38/)

[ Full BIP39 Wordlist ](/)