-tion or -sion? A Simple Spelling Rule You Can Tell from Verb Endings

-tion or -sion? A Simple Spelling Rule You Can Tell Just by Looking at the Verb Suffix

Have you ever gotten stuck mid-typing, wondering: Is it decision ✓ or decition ✗? Is it action ✓ or acsion ✗? These two suffixes sound almost identical, so it's no wonder we hesitate every time and often end up just guessing.

The good news is, -tion and -sion are not randomly assigned. In most cases, as long as you look back at "which verb this noun comes from," you can determine which one to use. Today, we'll teach you this simple rule. Once you learn it, spelling long words will become much more reliable.

This article continues the core framework of our "Word Decoding" series: prefixes change the meaning, roots contain the core meaning, and suffixes change the part of speech. If you haven't read the main article, Don't Panic When You See a New Word: 3 Steps to "Decode" Meaning with Prefixes and Suffixes, read that one first before coming back; it will make much more sense.

First, Understand: -tion and -sion Do the Exact Same Thing

First, let's establish the most important concept: -tion and -sion mean the exact same thing. Both are suffixes used to turn verbs into nouns, representing "a certain action" or "the result of an action."

• act (to act) → action (action, movement)
• decide (to decide) → decision (decision)
• discuss (to discuss) → discussion (discussion)

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

The Trick: Look at the Ending of the Original Verb

Here it is, the decision-making method you should take away today. When you want to spell a noun, first look back to find which verb it comes from, and then check how that verb ends.

If the verb ends in -de, -se, or -ss, the noun usually changes to -sion.

Let's walk through it:

• decide → decision (decision)
• conclude → conclusion (conclusion)
• divide → division (division)
• discuss → discussion (discussion)
• express → expression (expression, facial expression)

Do you see it? When the end of the verb has a "d" or "s" sound, the noun naturally takes -sion, making it smoother to pronounce.

Conversely, most other verbs use -tion when turning into nouns. This is the most common suffix and the one you should guess first:

• act → action (action)
• educate → education (education)
• create → creation (creation)
• celebrate → celebration (celebration)
• protect → protection (protection)

Let's see how they feel in sentences:

We made a big decision together. (We made a big decision together.)

Thank you for your protection. (Thank you for your protection.)

A Simpler Way to Remember It

If the rule above has too many details and is hard to remember, don't worry. Here is a more simplified version:

Guess -tion first, as it is the most common; only a small number of verbs ending in -de / -se / -ss use -sion.

Treat -sion as the "minority that needs special memorization," and write -tion for everything else first. Your accuracy rate will be very high. This is the same strategy we used in the article on -able / -ible: memorize the smaller group, and leave the rest to the general rule.

There are actually only a few common -sion nouns; you can treat them as a whitelist just by looking at them once:

• decision (decision)
• conclusion (conclusion)
• discussion (discussion)
• expression (expression)
• television (television)
• permission (permission)

For anything not on this list, guess -tion first, and you will be highly accurate.

Double-Check with Right vs. Wrong Examples

Apply this trick to the words you hesitate over most often:

• decision ✓, decition ✗ (decide ends in -de → -sion)
• action ✓, acsion ✗ (act is not -de / -se / -ss → -tion)
• discussion ✓, discustion ✗ (discuss ends in -ss → -sion)
• education ✓, edusion ✗ (educate → -tion)

Can I have your permission to leave early? (Can I have your permission to leave early?)

Let's start the discussion now. (Let's start the discussion now.)

Learn Other "Noun Suffixes" Along the Way

-tion / -sion is just one of the ways to turn a verb into a noun. In stages A1–B1, you will often encounter the following noun suffixes as well. Remember them, and you won't panic when you see long words:

• -ment: turns a verb into a noun, indicating "an action or result." move (to move) → movement (movement, motion), pay (to pay) → payment (payment)
• -ness: turns an adjective into a noun, indicating "a state or quality." happy (happy) → happiness (happiness), kind (kind) → kindness (kindness)
• -ity: turns an adjective into a noun, often indicating "degree or quality." real (real) → reality (reality), able (able) → ability (ability)
• -er / -or / -ist: indicates "a person who does something." teach → teacher, act → actor. We have a dedicated article explaining this group in detail, which you can read next: -er or -or? How to Choose the Right Suffix for a Person Doing Something.

His kindness made everyone feel welcome. (His kindness made everyone feel welcome.)

She has the ability to learn fast. (She has the ability to learn fast.)

Notice the common thread? These suffixes don't really change the meaning; they just change the part of speech. Once a verb or adjective becomes a noun, it can be placed in different positions in a sentence. This is exactly what the "Word Decoding" series has been saying all along: suffixes govern the part of speech.

A Quick Reminder, Just Relax

Languages always have a few words that don't follow the rules. They don't overturn your trick; they just require a bit more attention:

• A few verbs have slight spelling adjustments, for example, permit (to permit) → permission, admit (to admit) → admission, where the ending "t" changes to "ss" before adding -sion. When you encounter these kinds of words, just remember them as exceptions.
• If you are really unsure, type the word into a dictionary and check it, and use today's "look at the verb ending" trick to verify it on the spot. If you can get 80 to 90 percent right, you are already doing great.

Remember: tricks are great tools to help you quickly judge most situations. It is perfectly fine to leave a little room for exceptions.

How to Practice in Loopy

Knowing the rules is only the first step; truly remembering them comes from encountering them time and again in real sentences.

• Loopy's graded courses will put words like decision, action, and discussion into dialogues and contexts close to your level, allowing you to naturally absorb them within a context you understand, rather than rote-memorizing the spelling.
• When you search for an uncertain word, you can directly use the built-in dictionary to check its part of speech and example sentences, and apply today's "look at the verb ending" trick on the spot.
• New words you encounter will enter the memory curve review, popping up right before you are about to forget them to consolidate both spelling and meaning.
• If you want to practice speaking, listening, speaking, and shadowing will guide you to read these nouns aloud in sentences, helping your eyes, ears, and mouth memorize them together for a deeper impression.

Next time you get stuck on -tion or -sion, just look back at how the original verb ends. You will find that you could actually do it all along.

Choosing between -tion and -sion follows a rule, and taking them apart is the fastest way to internalize it: go to the word decoding training to break down words like action and decision into verbs plus suffixes. The moment you piece them back together, the rule will become second nature.