# duff

/ˈdəf/ (US) · /dˈʌf/ (UK)

Source: https://englishreference.com/word/duff
Updated: 2026-08-15

## Senses

### 1. broken or useless

adjective · CEFR B2 · British English · Informal

not working correctly or of very poor quality.

For teachers: defective, useless, or of inferior quality. This usage is highly characteristic of British colloquial speech.

- I bought a second-hand phone, but it turned out to be duff and won't even turn on.
- He spent the entire afternoon trying to repair the engine, only to realise he had been sold a duff alternator by the local scrap yard.

### 2. the buttocks

noun · CEFR C1 · American English · Slang

a person's bottom or backside.

For teachers: the buttocks. This term is generally considered mild and is often used in the phrase 'get off your duff' to encourage someone to be active.

- If you want to finish this project on time, you need to get off your duff and start working.
- The coach shouted at the players to get off their duffs and complete the final set of drills before the sun went down.

### 3. forest floor matter

noun · CEFR C2 · Technical

the layer of dead leaves and plants on the ground in a forest.

For teachers: the layer of partially decomposed organic matter, such as leaves and twigs, located on the forest floor above the mineral soil.

- The fire spread quickly because the dry duff on the forest floor caught fire easily.
- Ecologists measured the depth of the duff to determine how much carbon was stored in the forest's upper organic layer.

### 4. to mess up a shot

verb · CEFR C1 · Informal

to hit the ground instead of the ball in a game like golf.

For teachers: to mishit a ball, particularly in golf, by striking the ground behind it. This is typically used as a transitive verb.

- He was so nervous on the first hole that he duffed his shot and the ball barely moved.
- Despite his professional standing, the golfer duffed his opening drive, sending a large clod of turf flying further than the ball itself.

## Examples

- I think I bought a duff battery because it won't charge.
- The mechanic realized the car wouldn't start because of a duff spark plug that needed replacing.
- After hours of troubleshooting the electrical system, the engineer discovered that a single duff connection in the control panel was causing the entire machine to fail.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.