This is the 1796th most frequent Russian word.
коем
The word "коем" is an archaic or formal instrumental form of "который," meaning "by which" or "by some" in specific contexts.
This is a phrase expressing strict prohibition or advice, emphasizing 'not under any circumstances'.
Ни при коем случае нельзя опаздывать.
Under no circumstances should one be late.
Used to strongly deny the possibility of an action, again meaning 'not under any circumstances'.
Он ни в коем случае не сделал бы этого.
He would never, under any circumstances, have done that.
The word combined here emphasizes the flexibility or inclusiveness of conditions or states, similar to 'in whatever'.