The Complete List of
English Spelling Rules
Lesson 18: -ious or -eous
In this series of lessons, you will learn useful spelling rules in English.
This lesson will give you examples of two common adjective suffixes in English: -ious and -eous so that you can learn when to use each.
Download a free worksheet + answer key.
You have learned that an adjective in English describes a noun. You can often recognize adjectives easily because of their suffixes.
Two suffixes that always form adjectives are -ious and -eous. Unfortunately there are no firm rules to tell you when to use each, but reviewing the lists below will help you learn when to use each.
1. -ious with a short U sound
Poor Gerald is feeling very anxious about the presentation.
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The first thing to remember is that the adjective suffix -ious is much more common than the ending -eous. And of course, all the words ending in these two suffixes are adjectives.
There are two ways to pronounce the -ious ending. Sometimes the I is silent, so that the entire -ious ending is pronounced like "us" with a short U sound.
Here are some of the most common examples with this pronunciation:
- ambitious
- suspicious
- delicious
- religious
- superstitious
- conscious
- ferocious
- precious
- cautious
- vicious
- spacious
- prestigious
- gracious
- fictitious
2. -ious with a long E sound and a short U sound
Margaret told me a hilarious joke!
In the second way to pronounce the -ious ending, the I is not silent. It has a long E sound, followed by the short U sound, as above. So, the pronunciation of the whole -ious ending is "ee-us."
Here are some common examples of adjectives with this pronunciation:
- previous
- curious
- rebellious
- serious
- envious
- notorious
- glorious
- obvious
- victorious
- tedious
- studious
- various
- furious
- mysterious
- harmonious
- luxurious
- oblivious
3. -eous with a short U sound
Nora's sunflowers are gorgeous!
The adjective suffix -eous is much less common than -ious. However, it can also be pronounced in the same two ways we just saw above.
Here are the most common adjectives in which the -eous ending is pronounced like "us":
- outrageous
- homogeneous
- advantageous
- courageous
- righteous
- nauseous
- gaseous
4. -eous with a long E sound and a short U sound
Karen was very courteous when she welcomed Ben to the office.
Just like the -ious suffix, -eous can also be pronounced with a long E sound, than a short U sound: "ee-us."
Here are the most common adjectives with this pronunciation for the -eous suffix:
- spontaneous
- simultaneous
- hideous
- miscellaneous
- instantaneous
- erroneous
Review
So, let's review what we have learned about the adjective suffixes
-ious and -eous in English:- The suffix -ious
is much more common than -eous.
- There are no strict rules to tell you when to use each.
- Both these suffixes form adjectives.
- Both suffixes can be pronounced as "us" or as "ee-us." It
is best to learn these adjectives in groups by spelling and
pronunciation.
Download a free
worksheet
