millimetres
A millimetre is a metric unit of length that is equal to a tenth of a centimetre or a thousandth of a metre.
The creature is a tiny centipede, just 10 millimetres long.
那个生物是一只很小的蜈蚣,只有10毫米长。
It measures just one millimetre in diameter.
它的直径仅一毫米。