The word 突发 is formed by combining two individual characters, each contributing a core concept to create a new, integrated meaning. The first character, 突 (tū), carries the idea of "sudden" or "bursting forth", often implying something abrupt or unexpected. The second character, 发 (fā), fundamentally means "to issue forth", "to emit", or "to happen". When joined, the combination visually and conceptually depicts a scenario of something issuing forth suddenly. It is a direct semantic blend where 突 describes the manner and 发 describes the action, resulting in the holistic sense of a "sudden outbreak" or "emergency occurrence".