מלכים ב ו:ח פירוש: From David to Destruction ורש״י

Concealed, secret. [Targum Yonoson rendered,] “covered and hidden.” “פלוני” is an expression of, “If it be concealed [=יפלא],”⁴Devarim 17:8. it will be covered.⁵See Megillas Rus 4:1 and Rashi there.

Secret. Without a name, for he did not want it to be revealed.