calendar, calender

Calendar or calendar means the thing you use to keep track of the date, whether hung on a wall or digital--
We'll have to get a new calender before the first of the year.
If your computer doesn't work right, maybe you need to set the calendar.

Calender or calender ( rhymes with calendar ) means a machine that is used to press paper or cloth smooth--
The calender has large rollers to press the fabric smooth.
They will use a calender to coat the cloth with rubber.

Now that you know that, you can say--
"We used a calender to coat this cloth with plastic, to make a kitchen calendar that will wipe clean."

Note--not to be confused with a "colander", meaning a bowl-shaped strainer or sieve--
Put the beans in a colander to rinse them.
Pour the spaghetti into the colander carefully.