酥 (sū) describes food that is crisp and flaky, like pastry or fried snacks, with a light, crumbly texture. It differs from 脆 (cuì), which means 'crisp and crunchy' (e.g., raw vegetables, crackers) — 酥 implies a delicate, melt-in-the-mouth quality, while 脆 suggests a harder, snapping bite. 酥 also extends to mean 'limp, weak' (e.g., legs after walking) or 'silky' (e.g., hair), senses that 脆 does not share.