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What's the difference between UK and US English?

When you are writing your paper, you need to know whether US (United States of America) or UK (United Kingdom) English is required, which confuses a lot of people, even those who speak English fluently. Although they are very similar languages, there are several important differences that you must be aware of.

In general, if you mix up UK and US English spelling or grammar, the text will still be understandable, but not always. Some journals will accept either UK or US English, but many insist on one or the other, so it is important to get right.

Below is a little bit about the history of UK versus* US English, followed by a few examples. It is by no means a comprehensive list but will give you an idea of the things that you should be looking out for.
This blog article on the differences between UK and US English is written (mostly) in US English.

* This would be shortened to ‘vs.’ in the US but ‘vs’ in the UK!

Why are American and British English different?

The differences in spelling between UK and US English can be traced back to the 18th and 19th centuries and a combination of historical, cultural, and linguistic factors, as well as who wrote their dictionaries.

A major reason for the spelling differences is the isolation of the two countries and the fact that they developed in different ways. The UK was more industrialized and urbanized than the US, and this led to different forms of social and economic organization, which in turn led to different forms of language. Additionally, the US was a melting pot of immigrants, which led to a greater diversity of languages and dialects. The differences in spelling were reinforced by the education systems. In the UK, the education system traditionally included the study of Latin and Greek, which led to the preservation of traditional spellings of words. In contrast, the US education system has traditionally emphasized practical and vocational education, leading to a greater focus on spelling words as they are pronounced.

US English was influenced by Noah Webster, an American lexicographer (a person who compiles dictionaries) and language reformer. In the late 18th and early 19th centuries, Webster published a series of dictionaries and spelling books that aimed to create a distinct American version of the English language. He believed that the spelling of words should reflect their pronunciation, and he advocated for spelling reform to make the language more regular and consistent. As a result, he introduced a number of changes to the spelling of words, such as replacing the -our ending with -or, as in color instead of colour.

Another lexicographer that contributed to the differences in spelling was Samuel Johnson, whose dictionary, published in 1755, became the standard reference work in the UK. Johnson's dictionary was based on the traditional spelling of words, and it was widely used by British printers and publishers. Therefore, the traditional spellings of words were preserved in the UK, while in the US, the spelling of words was adapted to reflect their pronunciation.

UK versus US English spelling

There are many differences – too many to list here - but here are a few general guidelines that will cover many of them.

• UK English uses -ise endings for words such as ‘realise’ while US English (realize) uses -ize.

• UK English uses -our endings for words such as ‘colour’, while US English (color) uses -or endings.

• UK English uses -re endings for words such as ‘centre’ while US English (center) uses -er endings. This is particularly important for science units: ‘metre’ in the UK and ‘meter’ in the US.

• In the US, words like ‘traveling’ have one L but in UK English, there are two (travelling).

• An important one for your science paper is the difference in -yse/-yze endings. In the UK, it is ‘analyse’ and in the US, it’s ‘analyze’.

UK vs US Grammar

There are lots of differences between UK and US grammar and some of them are harder to understand than the differences in spelling but, again, if you mix them up, you will probably be understood. Here are a few important examples.

• UK English uses single quotation marks (') for quotation marks, while US English uses double quotation marks (").

• Full stops, or periods, in abbreviations. They are even called different things (UK: full stop, USA: period) and they are used differently in abbreviations. In the UK, they are often not used (Dr) but there’s a period following the abbreviation in the US (Dr.).

• The Oxford comma causes a surprising amount of controversy! The Oxford comma is after the penultimate item and before the ‘and’ in a list of items. In the UK, it is often – but not always! – omitted, but in US English, it is standard to include it.

UK English: The meal included meat, vegetables and potatoes.
US English: The meal included meat, vegetables, and potatoes.

• Collective Nouns are nouns that refer to groups. In UK English they are often plural but in US English, they are usually singular.

UK English: During the play, the audience held their breath.
US English: During the play, the audience held its breath.

What about Australian English?

Australian English is, mostly, more like UK English than US English, and Australian spelling tends to use the UK version. There are some differences between Aussie English and the UK. For example, Australians use collective nouns more like the Americans than the English.

However, although similar to UK English but borrowing a few bits from the US, the Aussie language is always evolving and there are lots of words that neither the British nor the Americans use. Fancy a ‘sanga’ (sandwich)? Or some ‘hot chips’ (UK: chips, USA: fries)?


English, wherever it is spoken, is a fascinating language but it is sometimes a bit complicated and the rules don't always make sense. If you’re not fluent in English, or even if you are but just want to improve your writing, get in touch with The Science Editor now!

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