松开 is a compound verb meaning 'to loosen' or 'to release' — literally combining 松 (sōng, 'loose' or 'relaxed') and 开 (kāi, 'open' or 'separate'). Together, they convey the action of undoing tension, unfastening something secured, or letting go of physical pressure. It’s commonly used with objects that are tied, gripped, held, or clamped — like ropes, buttons, handles, or even a person’s grip on something.

This verb is neutral in register and appears frequently in daily life: instructions (e.g., '松开安全带'), descriptions of physical actions ('他松开了拳头'), or even metaphorical contexts ('松开对孩子的控制'). It often takes a direct object (e.g., 松开绳子) and may be followed by aspect particles like 了 or 过. Unlike some similar verbs, 松开 emphasizes the transition from a tightened or held state to a relaxed or separated one — not merely 'opening' or 'removing'.