Which to use
“piston” and “poison” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.
- #15,677
- “piston” frequency rank
- #6,282
- “poison” frequency rank
- 21959
- confusion score
Side-by-Side Comparison
| Feature | piston | poison |
|---|---|---|
| Definition | A solid disk or cylinder that fits inside a hollow cylinder, and moves under pressure (as in an engine) or displaces fluid (as in a pump) | A substance that is harmful or lethal to a living organism when ingested. |
Where the eye mixes piston and poison
Muted = shared; highlighted = the visual trap. They share 5 letters in sequence. piston (CVCCVC) and poison (CVVCVC) run the same length but a different consonant-vowel pattern - the shape difference is usually the fastest tell.
Look-alike desk: piston vs poison
A purely visual mix-up. piston (/ˈpɪstən/) and poison (/ˈpɔɪ.zən/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they share most of their letters but differ in 3 positions. Our composite confusion score for this pair is 21959, derived from the frequency rank of both members and their visual similarity.
piston is recorded at frequency rank #15,677, classified as anoun, pronounced /ˈpɪstən/. poison is at rank #6,282, tagged as anoun, pronounced /ˈpɔɪ.zən/.
Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.
With a confusion score of 21959, this pair ranks #420,105 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of piston vs poison
Shared letters: inops. Private to "piston": t. Private to "poison": -.
"piston" · 6 letters · shape CVCCVC · "poison" · 6 letters · shape CVVCVC
Known mistypes of this pair
Frequently Asked Questions
Is swapping "piston" for "poison" ever safe?
Which is more common, "piston" or "poison"?
What to do next
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "piston" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "poison" - compare definitions side by side with the headword page. Word entry
- This pair ranks #420,105 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "piston" and "poison" also get mixed up with nearby pairs, the highest-scored neighbour is "pinion vs piston". Nearby pair
- Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes
Confusion rank #420,105 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.