infohazard
A piece of information which is directly harmful to one who knows it.
A basilisk, in this context, is information that can hurt you simply because you are aware of it. Yudkowsky uses the term 'infohazard'.
An information hazard; a piece of information which can be used to cause harm by one who knows it.
Where it comes from
Blend of information + hazard or info + hazard. Analogous to biohazard and possibly modeled after it.
Adapted from the Wiktionary entry infohazard (CC BY-SA 4.0).