user90638: In bitcoin wallet that support bip39 mnemonic code, is there a way to get the 12/24 words from the seed generated by them?
Or the translation is one-way only (from words to seed)?

user7272: There is no way to convert the resulting seed back to the original mnemonic.
As stated in the BIP 39 proposal:

To create a binary seed from the mnemonic, we use the PBKDF2 function
  with a mnemonic sentence (in UTF-8 NFKD) used as the password and the
  string "mnemonic" + passphrase (again in UTF-8 NFKD) used as the salt.

The seed (and optional passphrase) are passed through pbkdf2, which is not reversible.

90638: <p>In bitcoin wallet that support <em>bip39</em> mnemonic code, is there a way to get the 12/24 words from the seed generated by them?
Or the translation is one-way only (from words to seed)?</p>
 7272: <p>There is no way to convert the resulting seed back to the original mnemonic.</p>

<p>As stated in the <a href="https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki" rel="nofollow noreferrer">BIP 39</a> proposal:</p>

<blockquote>
  <p>To create a binary seed from the mnemonic, we use the PBKDF2 function
  with a mnemonic sentence (in UTF-8 NFKD) used as the password and the
  string "mnemonic" + passphrase (again in UTF-8 NFKD) used as the salt.</p>
</blockquote>

<p>The seed (and optional passphrase) are passed through pbkdf2, which is not reversible.</p>
