Organize and organise are the same verb: to arrange something so it works efficiently, or to plan and coordinate an event. Organise is the standard British spelling, so a school helping organise a fundraiser would keep the s, while an American style guide would use organize.
The core difference
The verb has one meaning; British English spells it organise, American English organize.
- organise — standard British spelling: She helped organise the school fundraiser.
- organize — American spelling of the same verb: We need to organize the files before the audit begins.
How to tell them apart
Organize traces back through Old French organiser to Medieval Latin organizāre and ultimately Greek órganon. Organise comes from the same family by way of Middle French, and by surface analysis simply adds the verb-forming suffix -ise to organ. Both spellings are accepted in British English style guides, though -ise is far more common there; American English uses only -ize.
Where it shows up beyond spelling
Organize and organise also cover forming or joining a labour union for collective bargaining, as when warehouse workers vote to organise. The spelling rule is the same in that sense: pick -ise for British audiences and -ize for American ones, and keep the choice consistent across a document.
