expletive

a. 填补的(补足的,附加的,多余的)
n. 填补物

He uttered several vigorous expletives when he dropped the iron on his foot.

他的熨斗掉下砸在脚上, 他随口骂了几声.

`Damn!' is an expletive.

｀该死!＇是咒骂语.