circular definition??

[sagrawal]

Can anyone please explain what exactly a 'circular defination' mean? I have seen this as a choice in plenty of CR questions, but am unable to analyze what it could mean. A sample where this is used is at http://www.urch.com/forums/showthrea...lar+definition (As one who has always)
Many thanks!

[ramanathansankar]

A: I like sugar
B: Why?
A: Because it is sweet
B: Why do you like something that is sweet?
A: Because I like sugar

This is a simplistic example of circular definiton