The word 敏感 is formed by combining two characters, each contributing a core meaning to create a new, unified concept. The first character, 敏 (mǐn), carries the idea of being quick, sharp, or agile, often in perception or thought. The second, 感 (gǎn), means feeling, sensation, or sensitivity. When joined, they describe a state where one's feelings or perceptions are exceptionally quick and sharp, hence, being highly reactive or easily affected, which is the essence of "sensitive" or "susceptible".