Bone of contention is an idiom describing an ongoing argument or discussion over a topic or issue. Some dictionaries list this phrase on its own, while others give bone the definition of a topic or issue and use of contention as a common modifier.
The plural is bones of contention.
The commonly accepted origin of the phrase is the image of two animals, usually dogs, fighting over the last bone of dinner.
A similar phrase bone of dissension was used in the sixteenth and seventeenth centuries, but fell out of favor. Either the phrase morphed into the current bone of contention or contention evolved freely and outpaced the other in popularity.
Examples
Low attendance has become a bone of contention between students and the management of a city college, even as the II PU final exams began on March 12. [The Hindu]
Earlier, the court had allowed Dasgupta and other petitioners to file their responses to the NDA government’s fresh guidelines which would “supersede” the UPA regime’s policy on price fixation for natural gas, including that from KG basin, which has been the bone of contention between the Centre and RIL. [The Economic Times]
When it comes to religious, cultural or patriotic marketing, most bones are potential bones of contention. [The Guardian]
Transfers and postings, promotion of officers and land allotments were the main bones of contention. [The Express Tribune]
The biggest bones of contention will be whether Greece can secure a nominal debt haircut, or even some further aid, and the halting of its privatization program, imposed by the troika of international bodies which oversee its bailout, agreed upon a few years ago. [CNBC]