How many kinds of circles are there, and what are they?

Kinds of circles? You mean tires & donuts? What of question is this and what is it?

Euclid’s definition. A circle is a plane figure bounded by one line, and such that all right lines drawn from a certain point within it to the bounding line, are equal. The bounding line is called its circumference and the point, its center. — Euclid, Elements, Book I.

In math, there is only one kind of circle.

Individual circles vary only by location, orientation, and radius, but not by kind.

In art, anything goes… ;-)

Thanks @Hawaii_Jake and @Zaku.
I thought the ic in concentric was an indication that it was a kind of circle. I thought “Isn’t a circle is a circle? ....How can there be different kinds of circles, What does a concentric circle look like?” And what are the other kinds?”

Since there are only two sides to a circle, I’ll say inner and outer.
After just checking my Merriam-Webster’s Collegiate Dictionary, 11th ed., there is no meaning implied to circles in the adjective suffix or noun suffix of ”-ic.”.

The only circles I know of are round ones. That is all I know. BUT I do know Pi.

The adjective concentric usually refers to several circles collectively, not any individual circle. Concentric simply means having the same center. The word typically refers to several circles of different sizes centered on the same point, e.g., a typical archery target.

Alright. I wonder how they decided on that word. I also note it’s concentric circles not circle which makes all the difference.

con = with / together
+
centr = center
+
ic = having that aspect
+
circles = a group of circles
=
A group of circles having the aspect of having the same center.

@Zaku Thanks.