A language indicates the plurality of a noun by changing its stem vowel.  In Maricopa, <i>humar</i> 'child' becomes <i>humaar</i> 'children.'  In English, irregular plurals like <i>men</i> and <i>geese</i> are formed in this way, from <i>man</i> and <i>goose</i> respectively.

<br><br><b>Reference</b><br>
Dryer, Matthew S.. 2008. Coding of Nominal Plurality.
In Haspelmath et al (2008), chapter 33. Available online at <a href="http://wals.info/feature/33">
http://wals.info/feature/33</a href>.
