"Pepper"
Cryptographers can never let a metaphor alone; they must extend it with further analogies and bad puns. "Peppering" is about using a secret salt, i.e. a key. If you use a "pepper" in your password hashing function, then you are switching to a quite different kind of cryptographic algorithm; namely, you are computing a Message Authentication Code over the password. The MAC key is your "pepper".
Peppering makes sense if you can have a secret key which the attacker will not be able to read. Remember that we use password hashing because we consider that an attacker could grab a copy …