The term 'Major Leagues (slang)' can be summarized as referring to the highest level of a particular activity or profession. The term is often used in sports, where it refers to the top professional leagues such as Major League Baseball, the National Basketball Association, and the National Football League. It can also be used more generally to refer to any field or profession where there are levels of expertise or achievement. For example, someone might refer to the 'major leagues' of business or politics. The crossword solution for this term is 'BIGS', which is an acronym for 'Big League Sports'.