Formal and Informal Vocabulary

This entry is about differences in vocabulary of formal and informal styles. For general differences, see this article.

Both formal and informal vocabulary can be found in all spheres of the language. As the language becomes more liberal, combining these two groups of words gets more common. Below is an example list of words and expressions in formal and informal registers.

What does ‘formal’ mean? Simply put, it means something or someone following established norms, traditions and habits. A formal letter should have certain structure and vocabulary, usually more official and strict. Think of formal as a rough synonym for ‘official’.

Vocabulary for letters

To ask for helpTo request assistance
To tell, to let knowTo inform, to notify
Speak toAddress smb.
Talk aboutDiscuss, consider
Fix, take care of, put rightRectify, amend
I think that …I believe/hold it that …
I want to …I wish to …
I’m ready to …I am willing to …
I’m angry about …I am dissatisfied with …
Deal with, take care ofManage, resolve, settle
Put up withTolerate, bear, endure
Bring upMention
Take awayRemove
ThanksI am grateful/thankful for …
I’m sorry about …I regret about …
I’m writing aboutI am writing regarding
I’ll get in touch …I will contact …
If you have any questionsShould you have any questions

General formal and informal vocabulary

AndAs well as …
So, in this mannerThus
If …Should … /Whether …
If … or notWhether … or not
For sure/CertainlyDefinitely/Assuredly

It is recommended to stick to either formal or informal words whenever possible. In other words, don’t mix two registers. It is as important as consistency in using English and American spelling. However, using two registers in your speech is not a serious error. At least as least as far as your speech is concerned. You should nevertheless pay attention to your writing — if you can use a less colloquial expression in your formal letter then you should do so. Sometimes mixing can’t be helped — for example, using phrasal verbs in a text. Phrasal verbs give life to your writing, so you shouldn’t abstain from using them. But such things as contracted forms or slang words — they do not belong in a formal text.

Which register should I use?

The degree of formality is usually decided by the following factors:

  • How well you know the person you’re writing to — the better you know the person, the less formal your writing will be (within reasonable limits)
  • The purpose of your letter — business correspondence tends to be more formal
  • The relative position of the person you’re writing to — a letter to your boss will be strictly formal. A letter to your subordinate is more likely to be semi-formal or fairly informal.

Use your judgement and common sense to decide on the register. For example, a letter to your boss who is much older than you, but whom you know very well is likely to be semi-formal, despite of his age and position. Conversely, if you are the head of department writing to a junior staff member whom you do not know, your letter should be on the formal side.


Bottom line is: if you are unsure whether to use formal or informal words, then stick to more respectable and tactful formal vocabulary. Nobody is going to hate you for being too formal. You will get a funny look or two if you overshoot with formality, but that is definitely not the end of the world!

On the other hand, opting for informal style and vocabulary in certain situations may be tactless and even rude. This in mind, use this simple rule:
When in doubt, keep it formal!

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