A bonnet is a hat tied under the chin, worn by babies and historically by women, though in British English the same word can mean a car’s engine cover.
For the full breakdown, see our best Bonnet guide.
If you searched “what is a bonnet,” the answer depends almost entirely on where the speaker lives and what they’re pointing at. In the United States, the word almost always refers to a soft hat with ties, the kind you see on newborns or in period dramas. Across the Atlantic, the same word can send you looking at a car’s front end. Here’s the full breakdown.
The Headwear Definition Most Americans Mean
In North American English, a bonnet is a hat tied under the chin. Dictionaries describe it as typically soft, with ties or ribbons that secure it beneath the jaw. These hats were standard for women from the 18th through the early 20th centuries, and they remain a familiar sight in historical fashion.
Today, the style survives in two places: on babies and in historical or cultural contexts. Bonnets are still a common accessory for infants, valued for keeping a baby’s head warm and shielding it from the sun. You’ll also see them in period films, at reenactments, and in the dress of certain religious communities that maintain traditional women’s head coverings.
The defining feature that separates a bonnet from other hats is the chin tie. A wide-brimmed sun hat doesn’t qualify; a soft-crowned hat that fastens under the chin does.
When Bonnet Means Car — The British Usage
In British English, “bonnet” is the word for the metal cover that sits over a car’s engine. If you hear someone in the UK say they need to pop the bonnet, they mean opening that hinged panel to check the oil or jump-start the battery. In the United States, that exact same part is called the hood.
This is the most common source of confusion. An American reading British media or watching a UK car review might picture a hat when the writer is describing a car repair. The reverse happens too: Brits encountering the US term “hood” often picture a gangster or a sweatshirt before connecting it to a car.
Both words are correct — they just belong to different dialects. Knowing which one your audience uses avoids a substantial misunderstanding.
Other Less Common Meanings
Beyond the two main definitions, dictionaries record a few narrower uses. In Scotland, “bonnet” can refer to a man’s or boy’s cap, a style distinct from the tied women’s hat. You’ll also find the word used in technical contexts to describe a protective covering or a hood-like part on machinery — a usage that echoes the British automotive sense.
These edge cases are rare in everyday speech. If you encounter “bonnet” and the necktie hat and car cover don’t fit the sentence, one of these alternatives usually will.
How To Tell Which Meaning Someone Intends
Context resolves almost every ambiguity. If the sentence mentions a baby, a nursery, or historical clothing, it’s the headwear. If it mentions an engine, a repair, or driving, it’s the car part. The speaker’s dialect is your second clue: Americans default to the hat, while British speakers are equally likely to mean either, depending on the topic.
If you’re in the market for a bonnet, knowing the distinction matters. For a baby bonnet, you’re shopping for a soft, tied hat. For a car, you’re buying a hood or engine cover — and you’ll want to search using the US term to find the right parts.
| Meaning | Where It’s Used | What It Describes |
|---|---|---|
| Headwear | US and UK (historical/baby wear) | A soft hat tied under the chin, worn by babies and historically by women |
| Car engine cover | UK only | The metal panel over the engine; called a hood in the US |
| Man’s cap | Scotland | A cap worn by men or boys |
| Protective covering | Technical/machinery contexts | A hood-like part covering a mechanism |
If you’re shopping for a bonnet to wear or to gift, the headwear meaning is almost certainly what you’re after.