Similar words with similar meanings

Is ‘competence’ the same thing as ‘competency’? What about ‘geographic’ and ‘geographical’, or ‘historic’ and ‘historical’?

Writers, editors and proofreaders often talk about homophones: ‘principle’ and ‘principal’, ‘complement’ and ‘compliment’, ‘discreet’ and ‘discrete’, for example. These are especially tricky because although they look quite similar and sound identical, their meanings are very different.
 
But there’s another type of confusable pairs of words that isn’t discussed so often: those where, as well as the spellings being the same, the meanings also have a lot in common.
 
I was going to call these ‘twin words’, but that already seems to have various other meanings, and I’d rather not add to the confusion. I don’t know of a recognised term for them, but if anyone can suggest one, I’d be keen to hear about it …
 
Let’s look at some examples that I often come across in my editing and proofreading work. The definitions I’ve used are from the following online sources:

• Oxford Dictionaries (using a Premium subscription)
• Cambridge Dictionary
• Merriam-Webster

​‘Competence’ and ‘competency’

The Oxford dictionaries define ‘competence’ as a mass noun (a singular noun representing something that can’t be counted, such as water or intelligence), meaning ‘the ability to do something successfully or efficiently’.

Meanwhile, they first define ‘competency’ as ‘a skill or ability, especially one required to perform a particular job or role’. This makes it a countable noun rather than a mass noun: it’s possible to have a number of competencies. But they also present it as an alternative to using the mass noun ‘competence’ as explained above.

Similarly, the Cambridge dictionary defines ‘competence’ as ‘the ability to do something well’, with ‘competency’ as an alternative word for the same thing – but also says a ‘competency’ is ‘an important skill that is needed to do a job’.

So, for example, we might say someone has the competence to perform well in a multifaceted job because they have all the competencies – the particular skills – that it needs. But, perhaps confusingly, we also could use ‘competency’ to mean the overall ability to perform well in that job.

Both words also share a specific meaning in a legal context: ‘the legal authority of a court or other body to deal with a particular matter’ (Oxford). But ‘competency’ also can refer to ‘the ability of a criminal defendant to stand trial, as gauged by their mental ability to understand the proceedings’ (Oxford).

This all makes for quite a complex relationship between the two words, often making it difficult to decide which one to use. On top of all that, their plural forms are more easily confused than the singular ones: the visual difference between ‘competences’ and ‘competencies’ isn’t all that obvious if you’re reading quickly, and they also might sound quite similar, depending on the speaker’s accent and emphasis (this is even worth considering when you’re writing, as many people ‘hear’ the words in their head when reading).

​‘Geographic’ and ‘geographical’

This one is much simpler. There’s no widely recognised difference in meaning, and the Oxford, Cambridge and Merriam-Webster dictionaries all treat them as essentially just two versions of the same word, meaning ‘relating to geography, or to the geography of a particular area or place’ (Cambridge). There seems to be a tendency to prefer ‘geographic’ in the US and ‘geographical’ in the UK, though.

Sometimes, one of them may just ‘feel’ better than the other: let’s face it, ‘National Geographical’ would be a clunky name for a magazine.

​‘Historic’ and ‘historical’

These can both mean the same thing: ‘of or concerning history or past events’ (Oxford). However, in that Oxford definition, this usage of ‘historic’ is tagged as ‘archaic’. The Cambridge dictionary recognises it only in a specialised legal sense (‘A historic offence is one that was committed by someone in the past but that they were not charged with at the time’), and Merriam-Webster gives it a narrower meaning than ‘historical’ (‘known or established in the past’ – for example, ‘historic interest rates’).
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The more common meaning of ‘historic’ is quite different: ‘important or likely to be important in history’ (Cambridge). So, for example, a ‘historic’ moment for a nation is one that has special significance for it – not just any old moment that happened at some point in its history.

​Why does this matter?

Sometimes, as we’ve seen above, either of the two words can be used, with no risk of confusing or misleading the reader – but not always.

Where there’s at least a potential difference in meaning, it’s important to choose the word that commonly represents that meaning. I often find myself adding ‘al’ to the end of ‘historic’ when it just means ‘relating to history’, to cut out any risk of confusion.

Otherwise, the key is to be consistent. If you use ‘geographic’ in one sentence and ‘geographical’ in another, some readers may notice the difference, or at least feel that something isn’t quite right. It can give an impression of sloppiness and a lack of attention to detail.
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As part of an editing or proofreading task, I usually create or update a style sheet, including a word list. Whenever I come across the kind of word that we’ve looked at in this post, I’ll make sure it’s in that word list, and that it’s used consistently unless there are good reasons for any variations. This approach helps to create a smooth experience for the reader, and to protect the author’s or organisation’s credibility – these are two of the main reasons to hire an editorial professional to check your writing.