越界 literally means 'to cross a boundary' — 越 (yuè) means 'to cross over, surpass', and 界 (jiè) means 'boundary, limit, or domain'. Together, they form a verb describing the act of stepping beyond an accepted physical, legal, social, or ethical line. It’s commonly used in contexts involving territorial disputes, wildlife conservation (e.g., animals entering human settlements), professional ethics, or interpersonal relationships.

The term carries a slightly negative or cautionary connotation, implying that a line has been breached — whether intentionally or unintentionally — and often signals risk, conflict, or violation. While it can describe literal geographic crossing (e.g., border incursions), it’s frequently used figuratively: a journalist may be accused of 越界 when probing private matters, or a pet dog might 越界 by entering a neighbor’s yard. It’s more formal than casual speech but widely understood across registers.