cent

The root cent comes from Latin centum, the number 'one hundred.' For the Romans, a hundred was a natural unit for organizing the world — soldiers, years, and money were all counted in hundreds — so centum left its fingerprints all over English.

Start with time. A century is literally a group of one hundred — originally a hundred anything, but it settled on a hundred years. From there:

- centennial / centenary = a 100th anniversary. These pair cent (hundred) with the root ann/enn (year, from annus), so the word literally says 'hundred-year.' A centennial celebration marks a hundred years of something.

Next, money and proportion. The Latin phrase per centum meant 'by the hundred' — out of every hundred. English squeezed it into one word:

- percent = a rate per hundred (50 percent = 50 out of every 100).
- percentage = the noun for that proportion (a large percentage of voters).
- cent = one-hundredth of a unit of currency. A cent is to a dollar what a single step is out of a hundred — the smallest hundredth-sized slice. (The symbol ¢ even survives.)

Then, people. A Roman army was organized into units of a hundred, and the officer in charge of one was a:

- centurion = the commander of (roughly) a hundred men. cent (hundred) tells you exactly how big his command was.

Finally, measurement. In the metric system centum shrank into the prefix centi-, meaning 'one-hundredth':

- centimeter = one-hundredth of a meter.
- centigrade = a scale divided into a hundred degrees.

Notice the two faces of the root. Sometimes cent means a whole hundred (century, centurion); sometimes, through per centum, it means a hundredth-sized share (percent, cent, centi-). Either way, the anchor is the same number: 100.

(One warning: words like accent, chant, and incantation only look like they belong here. They come from Latin canere / cantāre, 'to sing,' and have nothing to do with 'hundred.' They are same-spelling impostors.)