Enemy lines are often used to refer to the territory controlled by an opposing army or force. However, there are many synonyms for this term that can be used to convey a similar meaning. Some of these synonyms include enemy territory, hostile territory, front lines, battlefront, and combat zone. Other possible options could be warzone, danger zone, hot zone, and contested territory. These synonyms can be used in different contexts and depending on the situation, one may be more appropriate than another. Nonetheless, these terms are all related to the idea of confrontations, clashes, and danger in a military context.