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Why English plurals say s, z or iz: the wug test

Three cards reading s cats, z dogs and iz buses beside the title, with z highlighted in lime
30seconds
The 30-second version

Say 'cats' and 'dogs' out loud and listen to the last sound. One is a hiss, the other a buzz, and 'buses' adds a whole extra syllable. English spells all three plurals the same way, yet you have never got one wrong.

Pick a word and guess its plural sound using the widget. The rule depends only on the last sound of the word: voiceless stays s, voiced becomes z, hissy sounds take iz. Jean Berko's 1958 wug test showed that children work this rule out themselves rather than memorising plurals.

Deep dive · 4 min
Deep dive · 4 min

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