It's too hot, so I turned my old jeans into a pair of cutoffs to wear.

cutoffs 是由动词短语 cut off（剪掉）加后缀 -s 构成的名词复数形式。cut off 表示"切断、剪掉"的动作，加上 -s 后指"被剪短的裤子"，特指将长裤剪短而成的短裤。