acid

"acid" is the #16 word in the official BIP39 English mnemonic wordlist. It is encoded as the 11-bit binary value 00000001111 (decimal index 15), placing it at the 1% mark of the full 2048-word list.

The 4-letter prefix "acid" uniquely identifies this word among all 2048 entries. At just 4 characters, "acid" is one of the shorter words in the BIP39 list, making it quicker to type during wallet recovery but potentially easier to confuse with similar short entries.

Positioned in the first quarter of the wordlist (index 15), "acid" starts with "A" — a letter group containing 136 words total. It is word #16 within that group. Words early in the list have lower binary values with more leading zeros, which can be relevant when analyzing raw entropy data.

In a 12-word seed phrase, each word encodes 11 bits of entropy. The probability of "acid" 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.