Bone contention means a fundamental disagreement or dispute on a critical matter. There are several synonyms for the phrase. One of them is 'core dispute'. It emphasises the government of the matter, which is essential to the problem at hand. Furthermore, 'fundamental incongruity' is another synonymous phrase that underlines the disharmony between two or more parties. 'Basic opposition' is another variation that underscores the fundamental opposition or difference underlying an issue. Additionally, 'primary dissent' highlights the central points or reasons why parties are in disagreement. Finally, 'essential disputation' is another similar phrase that focuses on the critical and indispensable aspects of a dispute. These synonyms for the phrase 'bone contention' all emphasize the central nature of a disagreement.