What do you call a person who is 100 years old or older? — Cindy, United States

Answer

A person who is 100 years old or older is a centenarian. Below you will find some quotes from news stories about centenarians, to show how this word is used. Meanwhile, here are some other words for people who are not quite as old as centenarians:

a person who is between 70 and 79 years old is a septuagenarian
a person who is between 80 and 89 years old is an octogenarian
a person who is between 90 and 99 years old is a nonagenarian
These words are for specific age groups, and they are used primarily in formal contexts. In casual conversation and informal writing, the polite word for an old person is senior or senior citizen, as in this example:  

Seniors (or senior citizens) qualify for a discount at most movie theaters.
 Referring to someone as an "old person" is considered very impolite.