www.alphadictionary.com

A drawing, usually more simple than elaborate. Often a preliminary drawing, to guide the creation of a more elaborate final product such as a fresco or tapestry.

Sometimes the drawing is, itself, the final product, as a political cartoon, brought to high (intellectual, not necessarily artistic) polish by such masters as Thomas Nast, Bill Mauldin and Herblock. And cartoons primarily for amusement, either as single images (Charles Addams, George Booth, Ed Koren) or panels (Walt Kelly (Pogo). Jeff MacNelly (Shoe)).

Or it can be used to describe a character or situation as not serious.

Revisiting this suggestion I was reminded that it can also be a verb. Which gives us cartoonery, too.

I see that it comes from the original idea of drawing such sketches on stiff paper, i.e. carton. Then it spread out from there.

Speaking of Herblock, he designed a US postage stamp. It's not a cartoon as we usually think of one, but it's very good: