塑性 (sù xìng) is a technical noun meaning 'plasticity' — the ability of a material, tissue, or system to be permanently reshaped without breaking, especially under stress or over time. The character 塑 means 'to mold' or 'to shape', while 性 denotes 'nature' or 'property'; together, they literally mean 'the property of being moldable'. This term is widely used in materials science, engineering, and medicine — for instance, when describing how bone, cartilage, or neural pathways adapt structurally in response to repeated stimuli or injury.

In Chinese medical and rehabilitation contexts, 塑性 often appears in discussions of neuroplasticity (神经可塑性, shénjīng kě sù xìng) or tissue plasticity, emphasizing the body’s capacity for functional reorganization. It is not used for everyday objects like clay or playdough (which would use more colloquial terms like 可塑性 or simply 柔软); rather, it carries a formal, scientific register and almost always appears in compound terms or academic/professional discourse.