- "Years old" is a phrase used to indicate the age of a person or thing. When it comes after the noun it modifies, we don't use a hyphen. The singular phrase "year old" is used when the age is one.
- "Year-old" also indicates the age of a person or thing, but we use a hyphen when it comes before the noun it modifies or if it acts as a noun on its own.
🐶 My dog is three years old.
In the first sentence, "three years old" comes after the noun "My dog," so it's written without a hyphen.
🐶 I adopted a three-year-old dog.
In the second sentence, "three-year-old" comes before the noun "dog," so it's written with a hyphen.
When to use "years old" without a hyphen
"Years old" without a hyphen is used as a predicative adjective after the noun it modifies.
When the age is one, use the singular phrase "year old," as in "My baby sister is one year old." As you can see, the age comes after the noun "my baby sister."
For all other ages, including zero, use the plural phrase "years old," as in "In most Western cultures, babies are zero years old when they are born." Once again, the age comes after the noun "babies."
"Years old" without a hyphen is commonly used after a linking verb (e.g., is, am, are, was, were).
Example sentences of "years old"
- She is 25 years old and just graduated from college.
- The historical artifact is over a thousand years old.
- My nephew will turn six years old next month.
- The company is more than 50 years old.
- He became a famous artist when he was only 30 years old.
- The antique clock on the shelf is 200 years old.
- The ancient ruins are believed to be around 2,000 years old.
- She looks much younger than her actual age; she's 45 years old.
- The scientist discovered a species of turtle that can live to be up to 150 years old.
- The oak tree in our backyard is 80 years old and still thriving.
Examples from the web
"This short documentary was completed when Madeleine was 107 years old, and I consider myself very fortunate to have known her." - The New York Times
"The average billionaire is 65 years old, according to Forbes’ latest ranking of the planet’s richest people, and the eldest is insurance tycoon George Joseph, who’s 101." - Forbes
"Researchers claimed last month that the Gunung Padang site in West java, Indonesia, is the world's most ancient pyramid and could be more than 25,000 years old." - The Guardian
When to use "year-old" with a hyphen
"Year-old" with a hyphen is used as a compound modifier before the noun it modifies. For example, in the sentence "I adopted a three-year-old dog," "three-year-old" comes before the noun "dog."
Additionally, "year-old" with a hyphen can be used as a noun phrase on its own. For example, you could describe how old your kids are by saying "I have a five-year-old and a ten-year-old."
1. It's always singular, no matter the age.
2. It's usually connected to the number with another hyphen, depending on the style guide.
Example sentences of "year-old"
- We adopted a two-year-old cat from the animal shelter.
- The little girl has an adorable three-year-old brother.
- The vintage car in the garage is a fifty-year-old classic.
- She has a ten-year-old laptop that still works perfectly.
- The school organized a special event for the five-year-old students.
- The documentary features a 96-year-old war veteran sharing his experiences.
- I have a twenty-year-old bonsai tree that I've been caring for since it was a sapling.
- The museum displayed a 400-year-old manuscript that was recently discovered.
- We celebrated our friend's son's birthday; he's now a seven-year-old.
- The historic house was restored to its original glory, preserving its hundred-year-old architecture.
Examples from the web
"Two weeks ago, the planet’s most unlikely film star turned from a Ugandan warlord to a nine-year-old kid who runs a homemade cardboard arcade out of his dad’s used-auto-parts store, Smart Parts, in East Los Angeles." - The New Yorker
"I discovered … a tiny 700-year-old forest within sight of North America’s busiest highway" - The Guardian
"New tests promise to tell you if you have the cells of a 30-year-old or a 60-year-old." - The New York Times
The use of "years old," "year old," and "year-old" over time
The Ngram graph below shows the use of "years old," "year old," and "year-old" from the 1800s to the 2000s. As seen on the graph, "years old" and "year-old" are used the most, with "year-old" gaining popularity in the last 100 years, while "year old" is not used as frequently.
FAQ
Should I put an apostrophe in "years"?
In the phrase "years old," you generally do not use an apostrophe. For example:
- He is five years old.
- The car is ten years old.
- She is twenty-five years old.
In these examples, "years old" indicates age directly, and there is no need for an apostrophe.
However, when expressing a span of time, such as "two years' experience" or "three years' time," you use an apostrophe to indicate possession or attribution.
So, to summarize:
- "Years old" (indicating age): No apostrophe.
- "Years' time" (indicating possession): With apostrophe.
Numbers and the suspended hyphen
A suspended hyphen is used when connecting two or more compound adjectives with a common base by suspending the hyphen after the first adjective. This is often done for conciseness and to avoid redundancy. This is particularly common with ranges of numbers. Here are some examples:
- Ten- and twenty-year plans: Here, "ten-" and "twenty-" share the common base "year," and the hyphen is suspended to avoid repeating it.
- Three- and four-bedroom houses: In this example, "three-" and "four-bedroom" share the common base "bedroom," and the hyphen is suspended.
- Five- and ten-mile races: "Five-" and "ten-" both share the base "mile," so the hyphen is suspended.
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