Muko
Keywords: Ko
Muko (無劫 or 無コウ, mukō, lit. "non-threat") is the Japanese go term for a false ko threat.
In this diagram, is muko.
If White plays at a after Black fills the ko, then Black can play b, White c, and then Black d.
In french, ko threat translates to menace de ko. And muko to menace de con :-)