foster
/ˈfɒstə/
Binary Representation
11-bit index: 01011100000 (decimal 736)
Position
#737 of 2048
Hex Index
0x2E0
4-Letter Prefix
fost
About "foster" in BIP39
"foster" is the #737 word
in the official BIP39 English mnemonic wordlist. It is encoded as the 11-bit binary value
01011100000
(decimal index 736), placing it at the 36% mark of the full 2048-word list.
The 4-letter prefix "fost" uniquely identifies this word among all 2048 entries. At 6 characters, it falls in the typical length range for BIP39 words, balancing readability with distinctiveness during manual wallet recovery.
Located in the middle section of the wordlist (index 736), "foster" belongs to the "F" letter group, which contains 106 words. It is the #86 entry in that group. Mid-range words have a balanced mix of 0s and 1s in their binary representation.
In a 12-word seed phrase, each word encodes 11 bits of entropy. The probability of "foster" appearing in any specific position of a randomly generated phrase is 1 in 2048 (≈ 0.049%). A complete 24-word phrase encodes 256 bits of entropy, providing security equivalent to a key space of approximately 1.16 × 10⁷⁷ — far beyond the reach of brute-force attacks.
Word #737 in the Other 9 BIP39 Wordlists
Every official BIP39 wordlist has exactly 2048 entries, so index 736 encodes the same 11-bit value
(01011100000) in every language.
A wallet configured for one of these languages would use this word instead of "foster":
Similar Words — Check Carefully During Recovery
Words sharing the first three letters "fos":
Reminder: the first 4 letters of every BIP39 word are unique across the whole list, so "fost" always identifies "foster".