25/08/2019
In the intricate world of the English language, certain sounds prove to be particularly elusive when it comes to spelling. One such sound is the 'shun' sound, often found at the end of many nouns. While you might instinctively think of '-tion', the reality is far more complex, involving '-sion', '-ssion', '-cion', and even the rare '-xion'. For anyone keen on precise communication, especially in technical fields like automotive maintenance where clarity is paramount, understanding these distinctions is incredibly important. This guide aims to demystify these common yet confusing suffixes, helping you to confidently choose the correct spelling every time.

Understanding the '-tion' Suffix: The Workhorse
The suffix '-tion' is by far the most common way to form a noun with the 'shun' sound. It typically denotes an action, state, or result. You'll find it appearing in thousands of English words, often transforming verbs into nouns. Its prevalence makes it the default choice if you're ever unsure, but it's crucial to understand when its 'cousins' are preferred.
Common Patterns for '-tion':
- Verbs ending in '-ate': Many verbs ending in '-ate' form their noun by dropping the 'e' and adding '-tion'. For example, 'create' becomes 'creation', 'decorate' becomes 'decoration', 'activate' becomes 'activation'. In the automotive world, think of 'lubricate' leading to 'lubrication' or 'accelerate' leading to 'acceleration'.
- Verbs ending in '-t' or '-te': Verbs like 'act' become 'action', 'instruct' becomes 'instruction', and 'correct' becomes 'correction'. Even 'ignite' gives us 'ignition', a crucial term in engine mechanics.
- After consonants (especially 'c', 'p', 'l', 'r'): Words like 'collection', 'description', 'option', 'portion', 'caution', and 'definition' all utilise '-tion'. Think about 'combustion' – the process of burning fuel in an engine – which clearly uses '-tion'.
- After vowels (excluding 'e' where '-ssion' is common): 'Ablation', 'devotion', 'elocution', 'intuition'.
The '-tion' suffix almost always produces the clean 'shun' sound ([ʃən]). It's the most straightforward and widely applicable of the group.
The suffix '-sion' is trickier because it can produce two different sounds: the 'shun' sound ([ʃən]) or the 'zhun' sound ([ʒən], like the 's' in 'pleasure'). Understanding which sound it makes often depends on the letter preceding it.
When '-sion' Sounds like 'shun' ([ʃən]):
This typically occurs when the base word ends in an 's' or 'l', or sometimes after 'r' and 'n' where there's no clear rule, making it somewhat unpredictable.
- From verbs ending in '-s' or '-ss': While many verbs ending in '-ss' take '-ssion' (see next section), some take '-sion'. For example, 'express' becomes 'expression', 'discuss' becomes 'discussion', 'impress' becomes 'impression'.
- After 'l': Words like 'compulsion', 'expulsion', 'emulsion', 'propulsion'. Consider the 'suspension' system in a car; this uses '-sion' after 's'.
- After 'r' or 'n': This is less consistent. 'Inversion', 'extension', 'apprehension'. However, remember 'insertion' or 'invention' use '-tion'. This is where direct memorisation of common words becomes helpful.
When '-sion' Sounds like 'zhun' ([ʒən]):
This is a crucial distinction. The 'zhun' sound commonly occurs when the base verb ends in '-d' or '-se'.

- From verbs ending in '-d' or '-de': 'Decide' becomes 'decision', 'invade' becomes 'invasion', 'corrode' becomes 'corrosion'. Think of 'erosion' or 'explosion'.
- From verbs ending in '-se': 'Confuse' becomes 'confusion', 'revise' becomes 'revision', 'supervise' becomes 'supervision'.
Deciphering the '-ssion' Suffix: The Double 'S' Rule
The suffix '-ssion' is less common than '-tion' but distinct from '-sion'. It almost exclusively produces the 'shun' sound ([ʃən]) and is typically found in words derived from verbs ending in '-mit', '-cede', or often after a double 's' in the root verb.
Common Patterns for '-ssion':
- Verbs ending in '-mit': These are very consistent. 'Transmit' becomes 'transmission' (a vital component in any vehicle!), 'permit' becomes 'permission', 'admit' becomes 'admission', 'commit' becomes 'commission'.
- Verbs ending in '-cede': 'Concede' becomes 'concession', 'recede' becomes 'recession'.
- Verbs ending in '-press': While 'express' uses '-sion', many 'press' verbs use '-ssion', like 'depress' becoming 'depression' or 'compress' becoming 'compression'.
The double 's' in '-ssion' is a strong indicator of the 'shun' sound, and it's less prone to the 'zhun' variation seen in '-sion'.
The Rare '-cion' and '-xion' Suffixes
These two suffixes are exceedingly rare in English and are usually found in words with specific Latin or Greek roots. They almost always produce the 'shun' sound.
'-cion': Almost Exclusively 'Suspicion'
The most prominent example of the '-cion' suffix is the word 'suspicion', derived from 'suspect'. You'll rarely encounter this ending elsewhere in common English vocabulary. It's a true outlier.
'-xion': From 'x' Roots
The suffix '-xion' is reserved for words derived from roots containing the letter 'x'. The most common example is 'complexion', relating to the appearance or nature of something, stemming from 'complex'. Another less common example is 'annexion', though 'annexation' is more frequently used. You might also encounter 'crucifixion'. These are highly specific and not part of everyday usage patterns.

Comparative Table: Suffixes for the 'Shun' Sound
To help solidify your understanding, here's a comparative table summarising the typical usage and sounds of these suffixes:
| Suffix | Common Sound(s) | Typical Preceding Letters/Verb Endings | Examples |
|---|---|---|---|
| -tion | [ʃən] (shun) | -ate, -t, -ct, -pt; after c, p, l, r, v, u, o, a, i | action, creation, instruction, definition, combustion, acceleration |
| -sion | [ʃən] (shun) OR [ʒən] (zhun) |
|
|
| -ssion | [ʃən] (shun) | from verbs ending in -mit, -cede, -press | transmission, permission, aggression, compression |
| -cion | [ʃən] (shun) | Rare; typically from 'suspect' | suspicion |
| -xion | [ʃən] (shun) | Rare; from roots with 'x' | complexion, annexion, crucifixion |
Frequently Asked Questions (FAQs)
Q: Why are there so many different spellings for the same 'shun' sound?
A: The primary reason lies in the historical development of the English language. English has borrowed heavily from Latin, French, and other languages. Different suffixes often reflect the original Latin roots or the way words were adapted over time. For instance, words ending in '-tion' often come directly from Latin nouns ending in '-tio', while '-sion' and '-ssion' frequently come from Latin verbs with different past participle forms or different endings that evolved differently in English.
Q: Is there an easy trick to remember when to use '-sion' vs. '-ssion'?
A: A good rule of thumb: if the base verb ends in '-mit' (like 'transmit'), use '-ssion'. If the verb ends in '-d' or '-se' (like 'decide' or 'confuse'), you'll likely get the 'zhun' sound with '-sion'. For other cases, especially after an 's' in the root, it's often '-sion' (e.g., 'express' -> 'expression'), but if the 's' is doubled or if the root is from a verb like 'cede', then '-ssion' is more common.
Q: How does this apply to automotive terms?
A: Automotive terminology provides excellent examples! Think of 'ignition' (from ignite), 'combustion' (from combust), 'acceleration' (from accelerate), 'lubrication' (from lubricate) – all use '-tion'. Then you have 'transmission' (from transmit) and 'compression' (from compress) using '-ssion'. And for '-sion', you have 'suspension' (from suspend) or 'corrosion' (from corrode). Understanding these patterns helps you not only spell correctly but also better grasp the underlying action or state described by the word.
Q: Are there any words that can be spelled with both '-tion' and '-sion'?
A: While rare, some words do have alternative spellings, though one is usually far more common or preferred. For instance, 'connexion' (with -xion) is an older or more British spelling, while 'connection' (with -tion) is now almost universally preferred. Generally, sticking to the dominant spelling is best to avoid confusion.
Q: What if I'm still unsure?
A: When in doubt, the best approach is to consult a reliable dictionary. Consistent reading and exposure to correctly spelled words will also gradually build your intuition for these patterns. Pay attention when you encounter new words with the 'shun' sound!
Mastering the subtle differences between '-tion', '-sion', '-ssion', '-cion', and '-xion' is a hallmark of strong English writing. While it might seem like a daunting task at first, understanding the common patterns and the origins of these suffixes can significantly improve your spelling accuracy. Whether you're describing the 'function' of a new engine part or explaining the 'transmission' of power, choosing the correct ending ensures your message is clear and professional. Keep practising, and soon these tricky endings will no longer be a source of confusion, allowing you to focus on the more exciting aspects of vehicle mechanics and maintenance!
If you want to read more articles similar to Mastering '-tion' and Its Tricky Cousins, you can visit the Automotive category.
