tough question
- difficultRequiring much effort
- challengingHard to accomplish
- stumperUnanswerable question
- puzzleChallenge testing ingenuity
- riddlePuzzling question to solve
dilemma · conundrum · brainteaser · tricky · hard · thorny · knotty · perplexing · baffling · interrogation · quiz · exam · interview · awkward · uncomfortable · squirm · pause · silence