The ears of the old stuffed rabbit had become floppy from years of wear.

floppy 是形容词，由动词 flop（松软地垂下）加上后缀 -y 构成，表示"松软的、下垂的"。floppy 常用来形容柔软无力、无法保持直立状态的东西，比如松软的耳朵、软盘等。