grandfather

American  

[gran-fah-ther, grand-] / ˈgrænˌfɑ ðər, ˈgrænd- /

noun

1. the father of one's father or mother.

2. a forefather.

3. the founder or originator of a family, species, type, etc.; the first of one's or its kind, or the one being longest in existence.

   the grandfather of all steam locomotives.

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verb (used with object)

1. to exempt (something or someone) from new legislation, restrictions, or requirements.

   The law grandfathered all banks already operating at the time of passage. He was grandfathered into the pension plan.

grandfather British  

/ ˈɡrænd-, ˈɡrænˌfɑːðə /

noun

1. the father of one's father or mother

2. (often plural) a male ancestor

3. (often capital) a familiar term of address for an old man

4. dialect a caterpillar or woodlouse

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Etymology

Origin of grandfather

late Middle English word dating back to 1375–1425; grand-, father

Explanation

Your grandfather is the father of one of your parents. If your grandfather is quite old and has dozens of grandchildren, it might be hard for him to remember your birthday every year. Everyone has two biological grandfathers, whether they've had the chance to know them or not. In some families, grandmothers and grandfathers are involved in raising and caring for their grandchildren, while in others a grandfather may have died or live very far away. Informally, a grandfather can also be someone who started or invented something: "Blues musician Robert Johnson was the grandfather of rock and roll."

Example Sentences

My grandfather, who was a 70-hour-a-week physician — graduated medical school in 1920 — took a look at me two hours after I was born and told my mom, “He’s gonna be trouble.”

From Los Angeles Times • Apr. 11, 2026

Among its residents: the mother, father, grandmother and grandfather of an ASU undergrad.

From MarketWatch • Apr. 10, 2026

My grandfather died in 1973 without ever fulfilling that promise, his life having been consumed by the internal and external conflicts that forged modern China.

From The Wall Street Journal • Apr. 7, 2026

My grandfather was named Fuchang—“wealth and prosperity”—a hopeful prayer for a life the land rarely provided.

From The Wall Street Journal • Apr. 7, 2026

And there it was, pretty much the worst punishment his grandfather could have laid down.

From "Half Upon a Time" by James Riley

Related Words

• ancestor
• grandpa
• patriarch