Commonly Confused Suffixes

Because many suffixes overlap in their meaning, it can sometimes be confusing to determine which one is appropriate to use with a particular base word or root. To make things even more complicated, many suffixes also have alternate forms that are used in particular contexts or have evolved as the more accepted version.
In this section, we’ll look at some of the most common pairs or sets of commonly confused suffixes. We’ll give a very brief overview of each below, but for detailed spelling rules, conventions, and lists of examples for each, you can continue on to the individual sections.

“-er” vs. “-or” vs. “-ar”

The suffixes “-er,” “-or,” and “-ar” are all used to create nouns of agency (persons or things that perform an action) from verbs. Of the three, “-er” is by far the most common, while “-or” is much more common than “-ar.” Because they perform the same function and are pronounced in the same way (/ər/), it can be difficult to decide which suffix is the correct one to use. Fortunately, of all the commonly confused suffixes, “-er,” “-or,” and “-ar” have the clearest spelling conventions indicating when each one is preferred.

“-tion” vs. “-sion”

The suffixes “-tion” and “-sion” are both used to create nouns from verbs (and, less commonly, adjectives and other nouns) to describe a state, condition, action, process, practice, or the result thereof. They are actually just permutations of the same suffix, “-ion,” but there are specific conditions that will dictate which one we use, so it’s worthwhile to consider them individually. For example, verbs ending in “-ize” will take the “-tion” ending when becoming nouns (e.g., generalize becomes generalization); verbs ending in “-mit,” on the other hand, will take the “-sion” ending (e.g., permit becomes permission).

“-able” vs. “-ible”

The suffixes “-able” and “-ible” are both used to form adjectives meaning “possible, capable of, suitable for, or causing.” Of the two, “-able” is much more common: it is what’s known as a “living” or “productive” suffix, meaning that it is still being used to create new words. For example, acceptable, honorable, palatable, etc.
The variant “-ible,” on the other hand, is only used in older words that have survived into modern English. Some common examples include accessible, comprehensible, and sensible.

“-ant” vs. “-ent”

The suffixes “-ant” and “-ent” are both used to form nouns of agency (persons or things who perform an action) and adjectives that describe a state or quality. They both derive from the conjugations of Latin and French verbs; in some cases, they seem to “attach” to existing base words (e.g., accountant, persistent), while other times they are adjacent to roots that could not exist on their own (brilliant, resilient).

“-ance/-ancy” vs. “-ence/-ency”

The suffixes “-ant” and “-ent” each have two related noun forms: “-ance/-ancy” and “-ence/-ency.” These are all used to describe a state, quality, condition, or action typically associated with an adjective or noun of agency described by “-ant” or “-ent.”
Many roots and base words can take all three endings (e.g., expectant, expectance, expectancy; dependent, dependence, dependency), but many others will only take one of the two possible noun endings (e.g., pregnant becomes pregnancy, but not pregnance; different becomes difference, but not differency).
Additionally, there are smaller subsets of words that will only be formed with “-ant,” “-ance,” “-ent,” or “-ence,” without having either of the other two endings. For example, the word decongestant is commonplace, but decongestance and decongestancy are not words; similarly, we can say preference, but not preferent or preferency.

“-ic” vs. “-ical”

The suffixes “-ic” and “-ical” both form adjectives meaning “of, resembling, characterized by, or relating to,” and they can be notoriously difficult to distinguish. In many cases, words can be spelled either way, with one ending being simply more common than the other. Other times, the “-ic” and “-ical” versions will have similar but slightly different meanings, making each one more suitable in particular contexts.
Unfortunately, “-ic” and “-ical” form one of the least predictable pairs of suffixes, and, though there are a few spelling conventions we can rely on, more often than not we simply have to memorize which spelling is correct—or at least preferred.

American English vs. British English Suffixes

In addition to the existence of suffixes that are in themselves easy to confuse, there are several word endings that are spelled slightly differently in American English (AmE) as opposed to British English (BrE). For example, color (AmE) vs. colour (BrE); center (AmE) vs. centre (BrE); defense (AmE) vs. defence (BrE); or realize (AmE) vs. realise (BrE). For more information on these and other spelling conventions, head to the section that deals specifically with American English vs. British English.

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