Spelling Systems — UK vs US at a Glance

Here's the thing. You write colour one day, color the next, stare at organise until it stops looking like a word — and somewhere online there's always someone ready to tell you you've "got the spelling wrong," as if there were one rulebook and you'd lost your copy.

There isn't one rulebook. There are two — British and American English — and they part ways in a small handful of predictable places. Not chaos. Patterns. Six of them do nearly all the work.

This page doesn't teach a single rule. It's a map. Find the split that matches the word that's bothering you, glance at the examples to be sure you're in the right place, then follow the link to the piece that actually sorts it out.

The six genuine splits

1. -our / -or colour [US: color], favourite [US: favorite], neighbour [US: neighbor]. The classic one everybody thinks of first — British keeps the u, American drops it. → A1a — The -our ending (UK) · A1b — The -or ending (US)

2. -re / -er centre [US: center], theatre [US: theater], metre [US: meter]. British keeps -re on a cluster of nouns; American flips them to -er. Not every -er word is American — only this cluster. → A2a — The -re ending (UK) · A2b — The -er ending (US)

3. -ise / -ize organise [US: organize], realise [US: realize], recognise [US: recognize]. The verb endings that fill essays and "change settings" buttons. American is firmly -ize; British usually prefers -ise but allows -ize too — which is where most of the arguing comes from. → A3a — The -ise ending (UK) · A3b — The -ize ending (US)

4. Single -l- / double -l- travelling [US: traveling], cancelled [US: canceled], labelled [US: labeled]. When you tack on -ed, -ing or -er, does the l double? British usually doubles it after an unstressed syllable; American usually doesn't. → A4 — Single vs double -l-

5. -ae- / -oe- vs -e- encyclopaedia [US: encyclopedia], manoeuvre [US: maneuver], foetus [US: fetus]. The fussy Latin and Greek words — medicine and science especially. British often keeps the ae or oe; American simplifies to a plain e. → A5 — The -ae-/-oe- vs -e- pattern

6. -ogue / -og catalogue [US: catalog], dialogue [US: dialog], analogue [US: analog]. British keeps the full -ogue; American often clips it to -og, though the longer form still hangs on in places. → A6a — The -ogue ending (UK) · A6b — The -og ending (US)

When it isn't a system split

Some words are just one-offs — grey/gray, tyre/tire, plough/plow, cheque/check. If you've checked the six above and your word still won't settle, don't go inventing a seventh rule. It's probably an irregular. → B1 — Irregular form differences

And if the real question is which system to pick and how to hold it steady — for a CV, a client who "likes British English," a house style — that's strategy, not spelling. → C1 — Choosing and sticking to a spelling system

A quick word on where the borders are, so you don't waste time hunting here for something that lives next door. Apostrophes and its/it's belong to Pillar 2. Hyphens and email vs e-mail belong to Pillar 6. Capital letters belong to Pillar 7. This hub owns one job: name the six real spelling-system splits and get you to the right article in a click.

→ Spelling Systems Hub (Pillar 8)

— Roger Fielding