The humble full stop: from plain language to haplography


Caryn Gootkin hopes readers have conquered their fears of the semi-colon after her last column. Today she explains why the humble full stop can become a powerful plain language tool and reveals its many functions.

One of the main principles of plain language is to keep your sentences short. This is based on the premise that people digest information better when it is fed to them in small chunks. Each sentence represents an idea; read together they build your message in the mind of your reader. Resist the temptation to load too much information into one sentence as your reader may not be able to process it all at once.

The most common way to end a sentence is with a full stop. (For my American readers – a period, a word I can never use without snapping at my husband while experiencing pain in my lower back.)

The rule of thumb is that the average sentence should contain 15-20 words. (You probably hate the idea of an average sentence as much as I do and I beg you never to write one. But let’s tolerate the concept in this context.)

Over the course of a piece of writing, vary your sentence length to make the text more readable but ensure that on average you don’t exceed this limit.  If you do write a longer sentence, make sure it’s well-structured. Use punctuation wisely: commas, colons and semicolons can all break up a sentence into manageable bites.

The US Plain Language Action and Information Network (PLAIN) is a group of federal employees from many different agencies and specialties who support the use of clear communication in government writing. Their advice: “Keep it short; it’s not a crime to use lots of periods.” (*rushes for the ibuprofen*)

How and when to use a full stop

The Oxford Dictionary online defines a full stop as “a punctuation mark (.) used at the end of a sentence or an abbreviation.” We can expand on this definition by listing its various uses.

  1. To mark the end of a sentence that is a complete statement.

Example: I’m sure I don’t have to give an example of this usage.

EXCEPTION: If the last word in the sentence ends with a full stop, you don’t need a second full stop. This, I just learnt, is called conventional haplography, meaning that the omission of the repeated mark is accepted and not a writing error. Contrast this with (unconventional?) haplography which is the term for mistakenly leaving out a letter or letters that is repeated in a word. Raise your hand if you knew that.

Example: She eventually graduated with a BProc.

EXCEPTION: Always place the full stop inside a quotation mark that ends a sentence.

Example: HG Wells chose the following epitaph: “I told you so. You damned fools.”

  1. To mark the end of a group of words that don’t form a complete statement but emphasise the previous sentence.

You are not going out dressed like that. Finished and klaar.

  1. In abbreviations that cut out the last part of a word


Wednesday Wed.

ante meridian & post meridian a.m. & p.m.

etcetera → etc.

If the last letter of the word is the end of the abbreviation, you don’t need a full stop.


Government → Govt

Mister → Mr

(Proprietary) Limited → (Pty) Ltd

Doctor → Dr

  1. After initials


A.A. Milne

John F. Kennedy

EXCEPTION: When initials form an acronym, you don’t normally need full stops.




American English used to encourage the use of full stops (although they called them periods) in terms such as U.S.A. Their style bible, The Chicago Manual of Style, now discourages this, which means we should refer to it as CMOS and not C.M.O.S.

When is a full stop not a full stop?

As we all know, when used in computing, including website and email addresses, the full stop is called a ‘dot’:


Something I am sure not all know is that the full stop used as a decimal separator in mathematics is called a glyph. Don’t say I don’t broaden your mind with golden nuggets.

And that ends this short column on a punctuation mark few ever think about. When I started writing, I never dreamed I’d come up with four separate uses and uncover two aliases. Who knows how many other functions this versatile and hardworking mark has? Not me.