Spelling Systems Cheat-Sheet
🎒 Teaching an 11–18-year-old? Read the young-learner edition →
Here's the thing — when a word looks "wrong", it's usually just the other side of the Atlantic, not a mistake. Use this to spot the pattern in a couple of seconds; the full teaching lives in P8 · Spelling, Morphology & Word Choice.
Each row is a pattern, not a word list, so once you've clocked the shape you'll catch most swaps on sight. Status marks how firm each one is: rule (fixed), tendency (strong lean, with real exceptions), variant (both genuinely fine within that system).
| Pattern | UK | US | Example | Note |
|---|---|---|---|---|
| -our / -or — rule | -our | -or | colour / color · honour / honor · favour / favor | Derivatives follow the base: colourful / colorful, behaviour / behavior. Home → P8 |
| -re / -er — rule | -re | -er | centre / center · theatre / theater · metre / meter | Some words end -re in both (acre, massacre) — not everything converts. Home → P8 |
| -ise / -ize — variant (UK) / rule (US) | -ise or -ize | -ize | organise / organize · realise / realize | Both are correct British spellings — Oxford style actively prefers -ize as the older form, so organize isn't an Americanism [US: Americanism]. A handful stay -ise in both (advertise, exercise, surprise). Home → P8 |
| single vs double -l- — tendency | double before a suffix | single before a suffix | travelled / traveled · travelling / traveling · traveller / traveler | Both double when the last syllable is stressed (compelled, controlled). And watch the reversal: the base word fulfil / enrol / skilful (UK, single -l) flips to fulfill / enroll / skillful (US, double -l). Home → P8 |
| -ae- / -oe- vs -e- — tendency | keep -ae- / -oe- | simplify to -e- | encyclopaedia / encyclopedia · manoeuvre / maneuver · foetus / fetus · oestrogen / estrogen | UK scientific and medical style increasingly accepts the plain -e- too (medieval is now standard both sides; fetus is common in UK journals). Home → P8 |
| -ogue / -og — tendency | -ogue | -og or -ogue | catalogue / catalog · dialogue / dialog · analogue / analog | US keeps -ogue in plenty of cases — dialogue and monologue are widely kept; -og is strongest in computing (dialog box) and tech (analog). Home → P8 |
Pro-Tip: Pick one system per document and hold it. Mixing colour with center is the giveaway that no house style was chosen — set your spell-checker to the target variety and let it flag the strays.
Common Mistake: Assuming every British word takes -ise and that -ize is American. Oxford-style British English uses organize, realize, recognize — that's a genuine UK option, not a slip.
This page finds the pattern; it doesn't teach it. For the why behind each one — the morphology, the confusables, the fuller word lists — head home:
- P8 · Spelling, Morphology & Word Choice — the owning article for every pattern above
- Master UK/US Index (Pillar 12 · piece 10) — searchable spelling and vocabulary look-up
- UK/US Practice Sets (Pillar 12 · piece 17) — drills to lock the patterns in
¶ Field Notes — free
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