Quid
British slang for one pound sterling.
A quid is one pound sterling. Five quid is £5. It is the ordinary spoken word for the currency across the UK, not slang in the sense of being obscure, just informal.
It has no plural
You say "twenty quid", never "twenty quids". The word stays fixed regardless of amount, which is the single most common mistake non-native speakers make with it.
Where the word comes from
Nobody is certain, which is worth stating plainly given how confidently the internet asserts otherwise. The most commonly offered explanation is the Latin quid pro quo, "something for something", which fits the sense of an exchange. Another points to the Royal Mint Paper Mill at Quidhampton in Wiltshire. Neither is settled. The word is attested in English from the late seventeenth century.
Other British money slang
| Term | Means | Notes |
|---|---|---|
| Quid | £1 | No plural form |
| Fiver | £5 | The note itself, or the amount |
| Tenner | £10 | Same |
| Score | £20 | Older, from the sense of "twenty" |
| Ton | £100 | Also used for 100 mph |
| Grand | £1,000 | No plural: "two grand" |
| Bob | 1 shilling | Obsolete: shillings ended at decimalisation in 1971 |
| P | penny / pence | Spoken as "pee": "fifty p" |
A note on obsolete terms
Britain decimalised on 15 February 1971, retiring shillings and old pence. Terms like "bob" and "half a crown" belong to that vanished system and are now purely historical, though older speakers still use "bob" loosely.