노답 means 'someone who is stupid and extremely obstinacy and nobody can take him to a right way'
Sometimes, 노답 is also used to express extremely bad situation as much as anybody can't solve the problem. (in this case, 답이 없다 is used more often than 노답)
Literally, 노 is an english word 'no', 답 is ' a solution' or 'a right answer'.
노답 is derived to 핵노답 to emphasize its meaning. suffix 핵 means nuclear power.
e.g. 철수는 다른 사람말은 무조건 무시하고 억지만 쓰는 노답인 인간이야.