Picture a number written over a group of people, not on its own. Eighty deaths means nothing until you know whether eighty came out of four thousand or forty thousand. The word puts the group under the number, so that places of different sizes can finally be laid side by side.
One branch
分母是誰
兩個意思用的是同一個算法。唯一的差別是分母那一圈畫在哪裡：整個地方的人口，還是某一種病、某一群人。
noun · B2
The number of people who die in a particular place in a particular year, counted for every 100 or every 1,000 people living there, so that one place or one year can be compared with another.
死亡率
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
death ratenoun
The number of deaths per given unit of population over a given period of time (usually per 1000 persons per year when not otherwise specified).
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。