-able or -ible? A simple drop-the-suffix rule to tell them apart

-able or -ible? A "remove-it-to-know" rule to tell them apart

When writing emails or doing homework, have you ever gotten stuck on things like: is it comfortable or comfortible? Is it visible or visable? Since both suffixes sound almost identical, it's no wonder you hesitate.

The good news is that these two suffixes actually hide a very clean pattern. Today, I'll teach you a "remove-it-to-know" trick to tell them apart. Once you learn it, you'll be able to spell most of these words correctly on your own without having to look them up in the dictionary every time.

This article continues the core framework of our "Deconstruct Words to Learn Vocabulary" series: prefixes change the meaning, roots carry the core meaning, and suffixes change the part of speech. If you haven't read the main article yet, you can read Deconstruct Words with Prefixes and Suffixes first, and this will make much more sense when you return.

-able and -ible are the same thing

First, the most important concept: -able and -ible mean exactly the same thing. They are both suffixes that turn words into adjectives, meaning "can be..." or "easy to...".

• read (to read) → readable (can be read)
• break (to break) → breakable (easy to break)
• see / vis (to see) → visible (can be seen)

So the difference is purely in the spelling, and has nothing to do with meaning. This is also why they are so easy to confuse—both suffixes do the exact same job, they just look different.

The Trick: Remove the suffix and see if what's left is a complete word

Here it is, the rule you need to take away today.

If you remove the suffix and what is left is still a complete, recognizable English word, you usually use -able.

Let's try removing them in practice:

• comfortable → remove it and you get comfort (comfort) ✓ a complete word → use -able
• enjoyable → remove it and you get enjoy (enjoy) ✓ a complete word → use -able
• acceptable → remove it and you get accept (accept) ✓ a complete word → use -able
• washable → remove it and you get wash (wash) ✓ a complete word → use -able

Now, let's look at -ible:

• visible → remove it and you get vis ✗ not a complete word → use -ible
• possible → remove it and you get poss ✗ not a complete word → use -ible
• terrible → remove it and you get terr ✗ not a complete word → use -ible

Do you see it now? -able is usually attached to a word you already know; -ible is often attached to a root of Latin origin that cannot stand alone as a word.

Let's see how they look in a sentence:

This sofa is really comfortable. (This sofa is really comfortable.)

The stars are visible tonight. (The stars are visible tonight.)

Checking correctness with example sentences

Let's apply this trick to common spelling hesitations:

• acceptable ✓, acceptible ✗ (accept is a complete word)
• enjoyable ✓, enjoyible ✗ (enjoy is a complete word)
• possible ✓, possable ✗ (poss is not a word)
• responsible ✓, responsable ✗ (respons is not a word)

Is it possible to finish today? (Is it possible to finish today?)

You are responsible for your own choices. (You are responsible for your own choices.)

High-frequency -ible list: memorizing these is enough

There are so many words ending in -able that it is impossible to memorize them all; however, words ending in -ible are relatively few and fixed. Therefore, the most effortless strategy is: memorize the common -ible words, and for almost anything else not on the list, use -able.

The most common -ible words you'll encounter in the A1–B1 stages:

• visible (can be seen)
• possible (possible)
• impossible (impossible)
• terrible (terrible / awful)
• horrible (horrible / scary)
• sensible (sensible / wise)
• responsible (responsible)
• incredible (incredible / unbelievable)
• flexible (flexible)
• edible (edible / can be eaten)

Use this list as a "whitelist": if you see a word that is not on it, guess -able first—your hit rate will be very high.

That's an incredible story. (That's an incredible story.)

These mushrooms are edible. (These mushrooms are edible.)

Two quick reminders, don't be alarmed

Language always has a few exceptions, but don't worry—they won't ruin your trick, they just require a little extra attention:

• Some words drop the final e when adding -able, for example use → usable, love → lovable. If you remove -able and add back the e, it is still a complete word, so the rule still holds.
• A few -ible words are actually complete words when you remove the suffix, such as sensible (sense), accessible (access). You can just memorize these using the high-frequency list above and treat them as exceptions.

Remember: a trick is just a handy tool to help you quickly judge most situations. If you come across exceptions not on the list, just look them up in the dictionary—there is absolutely nothing wrong with that. If you can spell eighty to ninety percent of them correctly, you're already doing better than most people.

How to practice in Loopy

Knowing the rules is only the first step; to truly remember them, you need to encounter them over and over in real sentences.

• Loopy's leveled courses place words like comfortable, visible, and responsible into conversations and scenarios that match your proficiency level, allowing you to absorb them naturally in a context where you understand the meaning, rather than rote-memorizing their spelling.
• If you look up a word you're unsure about, you can use the built-in dictionary to check its part of speech and example sentences, and apply today's "remove-it-to-know" trick to verify it right then and there.
• New words you encounter will enter your forgetting curve reviews, appearing again right before you are about to forget them, consolidating both spelling and meaning together.
• If you want to practice speaking, listening, speaking, and shadowing will guide you in reading these adjectives aloud in sentences, engaging your eyes, ears, and mouth together to make a deeper impression.

Next time you get stuck on whether to use -able or -ible, remove the suffix and take a quick look. You'll realize you've actually got this down.

Whether it's -able or -ible, words you deconstruct yourself are the hardest to forget: go to our word-deconstruction training to break these adjectives down into roots and suffixes, and then spell out new words yourself. The system will keep track of your accuracy.