A centimeter is a unit of measurement for length in the metric system, equal to one-hundredth of a meter. The word comes from centi-, meaning “hundred,” so 100 centimeters make 1 meter.

To picture a centimeter, look at a metric ruler: the numbered marks show centimeters. One centimeter is roughly the width of your pinky finger at the nail. A small paperclip is about 3 centimeters long. A typical U.S. dollar bill is about 15 centimeters long.

Scientists, engineers, and most countries around the world use centimeters for everyday measurements. If you're measuring your height in many countries outside the United States, you might say you're 140 centimeters tall instead of 4 feet 7 inches. Doctors often measure babies in centimeters, and carpenters might use centimeters when building furniture.

The abbreviation for centimeter is cm, written without a period. When you see measurements like 25 cm, that means 25 centimeters. The metric system, which includes centimeters, makes calculations easier because everything works in multiples of ten: 10 millimeters equal 1 centimeter, and 100 centimeters equal 1 meter.