Abbreviation at Start of Sentence
In formal and academic writing, avoid starting a sentence with an abbreviation. Prefer to use the complete term instead.
- Poor: IR is invisible to the eye.
Better: Infrared radiation is invisible to the eye. - Poor: OSSs show changes to the Antarctic ice flow.
Better: Orbiting space satellites show changes to the Antarctic ice flow. - Poor: MCIs can now store unpleasant memories you wish to remove but not delete permanently.
Better: Memory chip implants can now store unpleasant memories you wish to remove but not delete permanently.
If using the full form results in awkwardness, try rephrasing.
- Poor: NSAIDs can, however, have serious side effects.
Better: However, NSAIDs can have serious side effects.
Of course, the use of abbreviations is a matter of style rather than grammar. If both rephrasing and using the full form are awkward, simply use the abbreviation instead to start the sentence.
- Unnecessary: Digital video discs are already things of the past.
Better: DVDs are already things of the past.
Starting a sentence with a capital-letter abbreviation may be acceptable when the alternative is awkward, but never start a sentence with a lowercase abbreviation.
- Incorrect: E.g., pelicans are gregarious waterbirds that form colonial nests.
Correct: For example, pelicans are gregarious waterbirds that form colonial nests.
Acronyms at start of sentence
Although abbreviations are not used to start a sentence in formal texts, acronyms (abbreviations pronounced as a single word) are generally acceptable in this position.
- Acceptable: COVID brought global aviation to a standstill.
- Acceptable: NATO officials are meeting in Paris today.
- Acceptable: UNICEF is now accepting internship applications.
- Acceptable: LAN access has been terminated for unregistered hosts.
- Acceptable: DOS applications can be run on an emulator.
In contrast, initialisms (in which the individual letters are pronounced) should be avoided at the start of a sentence. (NATO, NASA, COVID are examples of acronyms; USA, UK, UN are initialisms.)
Standard abbreviations at start of sentence
With standard abbreviations (such as UK, DNA, ATM, PhD, CEO), jumping through hoops simply to avoid starting a sentence with an abbreviation can be both awkward and unnecessary. Prefer to use the abbreviation itself in such sentences.
- Acceptable: UK health officials have released new quarantine guidelines.
- Acceptable: PhD students may apply.
- Acceptable: DNA tests revealed an anomaly.
Some abbreviated forms are listed as nouns rather than abbreviations in standard dictionaries such as Oxford and Merriam-Webster. Such abbreviations need not be expanded even when they appear at the start of a sentence (although rephrasing may sometimes improve readability). These terms are generally better known in their abbreviated than their expanded forms and don’t need to be explained in a document.
- Acceptable: ATMs have been upgraded with new security features.
- Acceptable: TV hosts are the new messiahs of the masses.
- Acceptable: DNA damage can result in sequencing errors.
Contractions at start of sentence
Although abbreviations are generally avoided at the start of a sentence, contracted social titles, such as Dr. and Mr., are acceptable in this position. Don’t spell out a social title just because it appears at the start of a sentence.
- Dr. Dash will see you now.
- Mr. Femy has an interview at 8 p.m.
- Prof. Lobo is the head of the philosophy department.
- Ms. Lopez is unavailable right now.
Symbols at start of sentence
Avoid starting a sentence with a symbol, numeral, or Greek alphabet that may appear in the name of a chemical compound. If doing so is necessary to avoid awkward structure, capitalize the first letter of the word connected to the symbol.
- β-Galactosidase is an enzyme that hydrolyzes lactose. In nonscientific texts, β-galactosidase is often referred to as lactase.
The word connected to the symbol is capitalized at the start of the sentence but lowercased in running text.
- N-Acetylcysteine is used to treat paracetamol overdose. Intravenous and oral formulations of N-acetylcysteine are available in most countries.
- 4-Phenylbutyric acid is a monocarboxylic acid that inhibits cell proliferation and invasion.