Cosy is the spelling to use in British English for something warm, snug and comfortable; cozy is the American form of the same word. A useful memory hook: cosy keeps the s of British spellings like realise and organise.
The core difference
Cozy and cosy describe the same warm, comfortable feeling; the difference is purely British versus American spelling.
- cosy — warm, snug and comfortable, British spelling: The café had a cosy atmosphere with soft lighting and armchairs.
- cozy — the same meaning, American spelling: We spent the evening in a cozy cabin with the stove lit.
- cosy — also a padded cover for keeping a teapot warm: She knitted a tea cosy to match the kitchen curtains.
How to tell them apart
Cosy comes from the Scots word cosie, of uncertain origin, possibly linked to the Norwegian kose seg, "to have a cosy time." American English later respelled it with a z, in line with its general preference for z over s in words like "organize".
Cozy can also carry a slightly critical edge, describing a relationship or arrangement that is a bit too close or convenient, as in a "cozy relationship between the regulator and the industry it oversees."
