Internecion is a rare word that is used to describe a destructive or deadly conflict between two parties. Some synonyms for the word internecion include bloodshed, carnage, annihilation, holocaust, and slaughter. These words all convey a sense of extreme violence and devastation, and are often used to describe the aftermath of wars, battles, or other catastrophic events. Other possible synonyms for internecion might include massacre, decimation, obliteration, and extermination, among others. In any case, these words all suggest a level of destruction and loss that is truly devastating, and remind us of the high human cost of conflict.