some situation or event that is thought about; "he kept drifting off the topic"; "he had been thinking about the subject for several years"; "it is a matter for the police"
an intricate knot tied by Gordius, the king of Phrygia, and cut by the sword of Alexander the Great after he heard that whoever undid it would become ruler of Asia
any very difficult problem; insoluble in its own terms
a question raised for consideration or solution; "our homework consisted of ten problems to solve"
a state of difficulty that needs to be resolved; "she and her husband are having problems"; "it is always a job to contact him"; "urban problems such as traffic congestion and smog"