The expression describes a puzzle, sometimes a crossword, characterised by its substantial problem and complexity. It suggests a puzzle that’s difficult to resolve, requiring appreciable effort and data from the solver. For example, a selected themed crossword with obscure vocabulary and complex wordplay may be characterised utilizing this phrase.
Such puzzles present a major cognitive exercise, stimulating problem-solving abilities and increasing vocabulary. They’ll provide a way of accomplishment upon completion because of the problem concerned. Crosswords of this nature have existed for many years, evolving from easier phrase puzzles to extra advanced and difficult constructions, reflecting growing solver ability and expectations.
