Merb.

A radical is a root symbol. Which is the root sign you could use to figure out the square, cubed etc. root of a number. And it's .. not.. on.. my keyboard! Yeah.. you need to have a number beside or in? the radical to show whatever root it is of.. I think.

So, for examples.. say the square root of 4, you would have the check mark thing and then a four, and the answer is 2.

Another example would be if you had the root check sign thing with a 3 above it or on it or something, it would be the cubed root of, say 6, and it would be 6 x 6 x 6 = 216. So the cubed root oh 216 is 6. Oh ma days.. I hate explaining things.. it works in my head, but its so hard to put into words! Oh, and I think I have to say where we use radicals? Yeah.. in math.. I have no clue where else.