noun
lop-eared; drooping ears
Describes ears that hang down, typically of dogs or rabbits. Often used as a noun or no-adjective.
うちの犬は垂れ耳で、とてもかわいい。
Our dog has floppy ears and is very cute.
垂れ耳のうさぎを飼っています。
I have a lop-eared rabbit.
立ち耳 means erect or prick ears, the opposite of 垂れ耳.
Compound of 垂れ (tare, 'hanging') + 耳 (mimi, 'ear').