karat or carat?
The British spelling is carat and karat is American English.
kerb or curb?
The British spelling is kerb for the edging of a street, while the American spelling is curb. Both American and British English use curb to mean 'limit' or 'control'.
key
This useful little word can sometimes be overused and, perhaps, imprecise. You could try important, vital, fundamental, solution etc. There are so many words in the dictionary, why insist on stretching this one so thinly?
kidnapped or kidnaped, kidnapper or kidnaper?
In British English the only two correct spellings are kidnapped and kidnapper. In US English, kidnaper and kidnaped are valid alternatives alongside the majority spellings kidnapped and kidnapper.
kilometre or kilometer?
The British spelling is kilometre and the American spelling is kilometer (not that either country likes to think in 'kilometres' anyway).
knelt or kneeled?
The British variant for the past participle of kneel is often knelt, though kneeled is also common. In the US kneeled is the only spelling. This is similar to 'learn', 'burn', 'spill' and 'lean'.
knots
Knots are a measure of nautical miles per hour, not distance. Therefore, make sure you don't say knots per hour.
knowledgeable or knowledgable?
The spelling knowledgeable is preferred in both the US and the UK, and the spelling knowledgable is an alternative spelling only used in US English.
koala or koala bear?
No matter how cute they may be, koalas are NOT bears. It is from this linguistic gem that that the whichenglish.com logo derives.
Kolkata or Calcutta?
Nowadays it's Kolkata.
krona
Swedish money is no longer referred to as 'crowns'. The modern form is krona, which means "crown" in Swedish. The plural is kronor. Iceland also has its own krona, but the plural there is kronur. Denmark and Norway have the krone and both use the plural kroner. Confusing, I know. At least Finland, where the currency used to be markka, now uses euros.
This page last updated: 15 November 2014
Jesse Karjalainen is the author of The Joy of English: 100 conversations about the English Language, Cannibal – the language and history of the discovery of the New World, and Roanoke – the language and history of Early Colonial America.