-able or -ible? -ant or -ent? Endings that sound alike

-able or -ible?

-able is the more common ending. The most useful guideline is that -able is usually added to a complete root word, and -ible usually follows something that isn't a complete word on its own.

• reasonable, dependable, considerablereason, depend, consider are complete words.
• horrible, terrible, incrediblehorr, terr, incred are not words.

If the root ends in e, the e is usually dropped (adore, adorable), except after a soft c or g, where it stays to keep the sound soft: noticeable, changeable. The adverb forms follow the same pattern: -ably and -ibly (considerably, horribly).

There are exceptions (sensible, flexible), so the guideline gives a strong first guess rather than a guarantee.

-ant or -ent? -ance or -ence?

Adjectives and nouns in this group come in families. If you know one member, you know the others:

So -ant pairs with -ance or -ancy, and -ent pairs with -ence or -ency. Another helpful clue: after a soft c or soft g the ending is usually -ent or -ence (innocent, intelligent, emergency), because a would make the letter hard. Where neither clue helps, as with existence or assistance, the word has to be learned.

-ous, -ious and -eous

-ous makes adjectives: enormous, tremendous, famous. When there's an 'ee' sound before the ending, it's usually -ious (curious, obvious, various). A smaller group uses -eous, including courageous and outrageous, where the e keeps the g soft.

• glamorousThe u from glamour is dropped. Same with humorous.
• mischievousThree syllables, no i before -ous.

Mischievous is often said and written as “mischievious”. Correcting the pronunciation usually corrects the spelling.

-le, -el and -al

All three make a similar 'ul' sound at the end of a word.

• -le is the most common: bicycle, struggle, vehicle.
• -el is used after m, n, r, v, w and often s, because -le never follows those letters: camel, tunnel, barrel, travel, towel, vessel.
• -al is often an adjective ending (natural, musical, chemical) and appears in some nouns (hospital, crystal).

For -al words, a related word often confirms it: nature, natural; music, musical; legal, illegal.

In the SATs

These endings are specifically listed in the Year 5 and 6 spelling appendix of the National Curriculum, and words such as reasonable, possible, confidence and dangerous are typical of the SATs spelling paper. Because the endings can't be heard, they also cause a lot of errors in children's independent writing.

Common mistakes

• incredableincred isn't a word, so incredible.
• existanceIt's existence: one to learn.
• noticableKeep the e after soft c: noticeable.

Teaching ideas

Is it a word?

Give pupils -able and -ible words. They cover the ending and decide whether what's left is a real word. Sorting by that test reveals the guideline, and the exceptions become a challenge list.

Word families

For -ant and -ent, give the adjective and ask for the noun, or the other way round. Children quickly learn that if they're sure of one form, the other follows.

Banned letters

Display m, n, r, v, w as “never before -le” letters. Pupils check words ending in 'ul' against the display and choose -el when one of those letters comes first.

Say it properly

For mischievous, glamorous and humorous, spend a minute on careful pronunciation before writing. Many errors in these words start in the mouth, not the pen.

Try it: five quick questions

SATs-style questions to use as a starter or a quick check. Tap to see each answer.

1. Which is correct? comfortible / comfortable

   Show answer

   comfortable: comfort is a complete word.

2. Which is correct? terrable / terrible

   Show answer

   terrible: terr isn't a word.

3. Write the noun from confident.

   Show answer

   confidence

4. Which is correct? tunnle / tunnel

   Show answer

   tunnel: -le never follows n.

5. Which is correct? mischievious / mischievous

   Show answer

   mischievous