Abbreviations — Grammar Rules & Examples

What are Abbreviations?

An abbreviation is any shortened form of a word or phrase. The three main types are truncations (a word cut short: Dr., Ave., etc.), initialisms (initial letters read separately: BBC, USA, CV), and acronyms (initial letters read as a new word: NASA, laser, radar). Each type has its own punctuation and usage conventions.

Whether to use a period (full stop) after an abbreviation depends on the type and the style guide. British English tends to omit periods in many abbreviations (Mr, Dr, St, US, UK), while American English inserts them more often (Mr., Dr., U.S.). Academic and professional writing usually follows one style consistently.

Latin abbreviations (e.g., i.e., etc., cf., et al., vs.) appear frequently in academic writing. They are often misused — especially e.g. and i.e., which have distinct meanings. In formal prose, their English equivalents ('for example', 'that is') are often preferred.

Three Types of Abbreviations

Identify which type an abbreviation belongs to before deciding on capitalisation, periods, and first-use conventions.

FormulaAbbreviation type → determines pronunciation, punctuation, and when to spell out on first use

Truncations (word cut short)

Abbreviation	Full form	Period — British / American
Dr / Dr.	Doctor	British: Dr (no period) / American: Dr.
Mr / Mr.	Mister	British: Mr / American: Mr.
Prof / Prof.	Professor	British: Prof / American: Prof.
St / St.	Street / Saint	British: St / American: St.
etc.	et cetera	period in both British and American
approx.	approximately	period in both styles

Initialisms (read letter by letter)

Abbreviation	Full form	First-use rule
BBC	British Broadcasting Corporation	spell out in full on first use in formal writing
USA / US	United States of America	often known — may skip spelling out in most contexts
CV	curriculum vitae	commonly known — may use without spelling out
GDP	gross domestic product	spell out on first use in academic writing
CEO	chief executive officer	spell out on first use unless audience definitely knows it

Acronyms (read as a word)

Abbreviation	Full form	Note
NASA	National Aeronautics and Space Administration	no periods; all caps; spell out on first use in formal writing
UNESCO	United Nations Educational, Scientific and Cultural Organization	no periods; all caps
laser	light amplification by stimulated emission of radiation	now a common noun — no caps, no spell-out required
radar	radio detection and ranging	fully absorbed into English as a common noun

How to Use Abbreviations Correctly

Spell out on first use

In academic, professional, and formal writing, spell out any non-obvious abbreviation in full on first use, followed by the abbreviation in parentheses. After that, use the abbreviation alone.

First use: The World Health Organization (WHO) published its report in March.
Subsequent uses: The WHO recommended a series of policy changes.
First use: The company reported an increase in gross domestic product (GDP).
Subsequent uses: GDP grew by 2.3 percent in the second quarter.

Tip: Well-known abbreviations (US, UK, EU, DNA, HIV) do not need spelling out in most contexts. Use your judgement based on the audience — a specialist audience in medicine does not need 'deoxyribonucleic acid (DNA)'.

Latin abbreviations: e.g., i.e., etc., et al., vs.

Latin abbreviations are common in academic prose. Each has a precise meaning. Using e.g. where i.e. is meant — or vice versa — is a significant accuracy error in formal writing.

e.g. (exempli gratia) = 'for example' — introduces one or more examples from a larger set
Several European capitals, e.g., Paris, Berlin, and Madrid, have introduced congestion charges.
i.e. (id est) = 'that is' — restates or clarifies a single thing
The proposal was rejected by a majority, i.e., more than half the committee voted against it.
et al. (et alii) = 'and others' — used in citations with multiple authors
The study by Hassan et al. found a significant correlation.

Tip: In formal British academic writing, 'for example' and 'that is' are often preferred over e.g. and i.e. in running prose. Latin abbreviations are more acceptable in parenthetical insertions: 'Some species (e.g., the common swift) migrate over 10,000 km.'

Title abbreviations before names

Abbreviations of titles (Mr, Mrs, Ms, Dr, Prof) precede names and follow British or American style for periods. In British English, no period is needed when the abbreviation ends on the same letter as the full word.

British style: Dr Ahmed, Mr Osei, Prof Chen
American style: Dr. Ahmed, Mr. Osei, Prof. Chen
Ms is the same in both styles: Ms Vasquez / Ms. Vasquez

Tip: Mrs (British) / Mrs. (American) is the abbreviation for 'Missus' — the full form is rarely written. Ms does not abbreviate a full word; it was created as a title-neutral alternative and takes no period in British style.

Abbreviation Warning Signals

e.g.'for example' — introduces examples, not a complete restatement

i.e.'that is' — restates or clarifies exactly one thing

etc.'and so on' — do not combine with e.g. ('e.g., cats, dogs, etc.' is redundant)

et al.'and others' — used in citations, not in running prose

First use in a textspell out non-obvious abbreviations in full → (abbreviation) on first appearance

Period after abbreviationBritish: often omitted in truncations / American: usually retained

e.g. vs i.e.

These two Latin abbreviations are frequently confused. 'e.g.' introduces examples from a set; 'i.e.' restates or defines precisely.

e.g. — introduces examples (not exhaustive)

Several factors influence test performance, e.g., preparation time, sleep, and anxiety.

'e.g.' signals that preparation time, sleep, and anxiety are examples — other factors also exist.

i.e. — restates precisely (exhaustive)

The deadline is at the end of the working day, i.e., 17:30.

'i.e.' specifies exactly what 'end of the working day' means — one precise restatement.

Common Mistakes

Using e.g. where i.e. is needed

✗ Only one candidate passed, e.g., the one with the highest score.

Only one candidate passed, i.e., the one with the highest score.

'i.e.' restates a single, specific fact — who that one candidate was. 'e.g.' would imply there were multiple passers and this is just one example, which contradicts 'only one'.

Writing 'ect.' instead of 'etc.'

✗ Bring your passport, ID card, ect.

Bring your passport, ID card, etc.

'etc.' is the abbreviation for 'et cetera'. The common spoken mispronunciation 'eck cetera' produces the spelling error 'ect.'

Not spelling out abbreviations on first use

✗ The IMF and WTO released a joint statement. The IMF noted that…

The International Monetary Fund (IMF) and the World Trade Organization (WTO) released a joint statement. The IMF noted that…

In formal writing for a general audience, spell out unfamiliar abbreviations on first use. Only abbreviations the entire target audience already knows (US, UK, DNA) can be used without introduction.

Mixing e.g. with 'etc.' in the same list

✗ Several cities, e.g., Paris, Rome, Tokyo, etc., have congestion charges.

Several cities, e.g., Paris, Rome, and Tokyo, have congestion charges.

'e.g.' already signals that the list is not exhaustive — adding 'etc.' is redundant. Use one or the other, not both.

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