balloon1/bəˋlun; bəˈluːn/n [C] a small coloured rubber bag that you blow air into and use as a toy or decoration 气球: Can you blow up these balloons ? 你能把这些气球吹大吗?Suddenly the balloon burst . 突然气球爆了。 HOT AIR BALLOON
balloon2v [I] to suddenly become much larger 膨胀﹐鼓起来: The company's debt ballooned to $350 billion. 公司的债务迅速增至 3500 亿美元。