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Usable or Useable: Which Is Correct?

You may well have seen both versions of this word in written English and wondered which one is correct. Many words in English have more than one spelling, and there are various reasons why this can be the case.

In terms of American English, “usable” is the most acceptable version. Internationally, both “usable” and “useable” are acceptable spellings of the word. Most dictionaries list “useable” as a variant spelling. You’re more likely to see it in places where British English is dominant.

In this article, we’ll delve into the origins of the words, research their popularity, and examine how variant spellings emerge. We’ll also review the rules for adding suffixes to words, particularly -able.

Usage and Origins of Usable/Useable

Etymologists, who study the origin of words and how their meanings evolve, date the earliest usage of the word back to 1300 when the English language adopted it from the French usable, meaning custom, experience, or habit (source).

Later in the 14th century, it came to mean the act of using something. Its roots lie in the Latin word usus, which means use or custom. Its usage became more common from the mid-1800s. 

Definition

The word usable/useable in its broadest sense only has one definition, but there are nuances in meaning. Consider the following sentences, which illustrate how we use it.

Meaning: convenient for use:

This building has 20,000 feet of usable office space.

Meaning: ready or fit for use:

Even though the bicycle is rusty, it is still usable.

Meaning: capable of being put to use (for a specific purpose):

The manufacturing process produces some usable byproducts.

Synonyms and Antonyms

There are many synonyms for “usable,” although it’s important to understand the context of a sentence before randomly replacing a word with a synonym. See the list below for some of the words that you can use in place of “usable” in various contexts:

  • Accessible
  • Adaptable
  • Applicable
  • Available
  • Convenient
  • Employable
  • Functional 
  • Practicable
  • Serviceable
  • Suitable
  • Useful
  • Valuable

In the context of the example sentences above, illustrating the nuances of meaning for “usable,” we can use the following synonyms: 

This building has 20,000 feet of available office space.

Even though the bicycle is rusty, it is still functional.

The manufacturing process produces some valuable byproducts.

Likewise, there are also various antonyms for “usable.” These include the following:

  • Inappropriate
  • Unadaptable
  • Unserviceable
  • Unsuitable
  • Worthless

Making Other Words from Usable/Useable

By adding other prefixes or suffixes, we can make other words from “usable.” As with usable/useable, we can spell all these words with or without the “e.” These include the following:

Reus(e)able: can be used again:

The store is insisting that its customers bring reusable shopping bags.

Unus(e)able: cannot be used:

The heavy rains have made our road unusable.

Us(e)ability: the degree to which something can be used:

She used a focus group to test the usability of her new website.

Us(e)ableness: quality of being us(e)able:

Her new curtains increased the usableness of her sitting room.

Popular Use

Various corpora look at linguistic data to provide insight into a language. The biggest of these is The Corpus of Contemporary American English (COCA) which boasts a database of more than a billion words. 

Since 1990, the COCA has added 25 million words annually from eight genres — spoken, fiction, magazines, newspapers, academic texts, TV and movie subtitles, blogs, and web pages (source).

A search on this database shows that for every occurrence of “useable,” “usable” appears more than nine times more.

The Oxford University Press established the smaller British National Corpus (BNC) in the 1980s. It houses 100 million words from similar categories, and a search on this database reveals similar results. 

While these corpora help us understand which word is more popular, it still doesn’t explain why people choose one or the other. It seems likely that people across the world more commonly employ “usable” but that standard usage has resulted in “useable” becoming accepted as a variant. 

Image by Aaron Burden via Unsplash

Variant Spellings

There is more than one correct way to spell certain words. When both are in everyday use, the dictionary will include them both (source). Usually, dictionaries enter the most common one first, followed by the less common one. Below is an example from the Merriam-Webster dictionary (source).

Usable: adjective

Variants: less commonly, useable

Definition:

  1. Capable of being used
  2. Convenient and practicable for use 

Variant spellings are another way of writing a word. Some people use these as an alternative to the generally accepted form. If they’re a recognized variant, then they’re acceptable. 

One rule of thumb, though, would be to apply the variant consistently. So if you’re going to use “useable,” then it’s probably best to also use “useability” for consistency.

British vs. American Spelling

It would be reasonable to wonder why spelling can differ if we’re all talking the same language. One of the main reasons for this is how the various words have evolved in their usage. 

As a broad rule, British English usually tries to keep the spelling of words it has borrowed from other languages, while American English tries to spell words as they sound (source).

People in the United Kingdom, as well as in its former colonies such as Australia, South Africa, and India, predominantly use British English. Interestingly, this is coming into flux as the influence of American English becomes more pervasive (source). 

English speakers in the Americas predominantly use American spelling. 

We outline the most common differences below.

British EnglishAmerican English
Words end in -our
E.g., colour, honour
Words end in -or
E.g., color, honor
Words end in -re
E.g., centre, meagre
Words end in -er
E.g., center, meager
Ends words -ise
E.g., realise, categorise
Ends words -ize
E.g., realize, categorize
Words end -ence
E.g., licence, defence
Words end -ense
E.g., license, defense
Uses the double vowels “oe” or “ae”
E.g., foetus, encyclopaedia
Replaces with simple “e”
E.g., fetus, encyclopedia
Words end in -ogue
E.g., catalogue
Words end in -og
E.g., catalog
Words end in -yse
E.g., analyse, paralyse
Words end in -yze
E.g., analyze, paralyze

These are merely a few of the more common differences, but there are many others. “Usable” is one of those, although writers more commonly use “usable” in both American and British English, and the “useable” spelling, while acceptable, is rare.

For more on the difference between British and American English, read our article, “Mom vs. Mum: What’s the Difference?

Adding Suffixes to Words

A suffix is a word ending or a group of letters added to a word root. A root word is a word that stands on its own but can make other words by adding letters before (prefixes) or after (suffixes) (source). 

Adding a suffix will often change the meaning of a word as well as what part of speech it is. For example, if we take the root word “talk,” we can add various suffixes to make it into a different word, such as “talked,” “talking,” “talkative,” “talker,” etc. 

Below is a table showing some of the more common suffixes and examples of how adding them to root words creates other words.

SuffixExampleSuffixExample
-edplay + ed = played-nesssoft + ness = softness
-ingwalk + ing = walking-alexperiment + al = experimental
-erjump + er = jumper-tioneducate + tion = education
-ableprint + able = printable-siondivert + sion = diversion
-lylove + ly = lovely-mentamuse + ment = amusement
-fullythank + fully = thankfully-fulhope + ful = hopeful
-estsmall + est = smallest-yfull + y = fully

Spelling Rules for Adding Suffixes 

Mostly, one simply adds the suffix to the root word. However, as with all language rules in English, there are exceptions. The rules below cover most suffix-related spelling:

RuleExample
Double the last letter when adding the suffix for single-syllable words that end in a single consonant.fun + y = funnyspin + ing = spinning
Double the “l” for words longer than one syllable that end in “l”.tunnel + ed = tunnelledtravel + ing = travelling
Double the last letter for words longer than one syllable that end in a single consonant where stress is on the last syllable when you say them.refer + al = referralbegin + er = beginner
Don’t double the last letter if the root word ends in a consonant and the suffix begins with a consonant.commit + ment = commitmentregret + ful + regretful
Change “y” to “i” in words that end in a consonant followed by “y” — except when adding “ing” to avoid a double “i.”happy + ness = happinessgrumpy + ly = grumpily

Spelling Rules for Words Ending in “e”

We will treat words that end in “e” as a separate category in terms of spelling rules, and “use” falls into this category.

If the suffix begins with a vowel (a, e, i, o, or u) or a “y,” then you usually drop the “e” before adding the suffix, as shown in the examples below:

able + y = ably

prime + al = primal

care + ing = caring

love + able = lovable

If we apply this rule to “use,” then it would follow that “usable” should be the correct spelling. “Useable” is, therefore, an exception, and many use it this way.

If the suffix begins with a consonant, then you keep the “e” and simply add the suffix, as shown in the examples below:

care + ful = careful

excite + ment = excitement

love + less = loveless

There are numerous exceptions to this rule, but, generally, the exception is the only correct spelling rather than accepting both alternatives as in the case of usable/useable. These include words such as courageous, changeable, and noticeable. 

One can argue that these words all retain the “e” to ensure correct pronunciation  because the sound of the final letter of the root word would change without the “e.” 

Image by Joshua Hoehne via Unsplash

Adding -able as a Suffix

If you add -able to a root word, it forms an adjective that broadly means “capable or worthy of.” Because it creates a new word, -able is a productive suffix and is one whose usage is quite frequent.

Consider the following examples, which all create a new word from the verb stem:

comfort + able = comfortable

admire + able = admirable

suit + able = suitable

teach + able = teachable

bear + able = bearable

If in doubt, refer to The Oxford New Essential Dictionary and Dreyer’s English. Both are reliable resources that can help to answer any questions you may have. You can buy them both on Amazon.

When to Use -able or -ible?

Although both mean the same, there are some instances when you add -ible rather than -able. This is one of the trickier nuances of the English language to master because they sound the same, and it’s hard to work out when the less common -ible is more appropriate.

As a rule of thumb, we mostly use -ible when forming an adjective from a word we derive from a Latin verb ending in -ire or -ere (source). However, given that most of us don’t have a working knowledge of Latin, it’s one of those things that we just have to learn.

The suffix -able is much more common, around six times more frequent, so it is usually the best guess (source). There are also a few general guidelines: 

  • Use -able when the root word is unchanged.
  • Use -able if you can make a word ending in -ation from the same root word. 
  • Use -ible when it’s hard to work out the root word.

This article was written for strategiesforparents.com.

Some notable exceptions to these guidelines include accessible, digestible, flexible, and suggestible. However, the examples below illustrate the broad rule. 

-able-ible
admirableaudible
advisablecompatible
comfortablefeasible
desirablecredible
laughableedible
movablefeasible
noticeablehorrible
preferableincredible
suitableinvisible
unbelievablenegligible
usablesensible

Final Thoughts

Creating new words by adding suffixes is an important part of mastering the English language. Root words can create myriad new possibilities when combined with the many suffixes on offer in English. One of the most useful is -able, making it possible to express the ability to do something.

Speaking is only one part of this, though, because, when writing, one also needs to master the various spelling rules. It’s never simple when there are exceptions to the rule and even more complicated when there are alternatives available. 

In the case of useable vs. usable, it’s best to go with “usable” because it conforms to the rules and is the most widely used.