I went to the fabulous Leonardo exhibition at London's National Gallery yesterday, and the word 'cartoon' was much in evidence. Leonardo's cartoons, such as the drawing nicknamed the Burlington House Cartoon (aka The Virgin and Child with St Anne and John the Baptist - see it here), use the word cartoon in its original sense, namely a preparatory drawing for a painting or fresco. The word cartoon comes from the Italian cartone, which is the stout paper on which drawings were originally made.
For a couple of centuries this is what cartoon meant, but then in the 1840s the satirical magazine Punch used the term to describe the comic drawings and caricatures it began to publish. According to Wikipedia the term was meant to be ironic and a reference to the self-aggrandising posturing of Westminster politicians. Film cartoons were originally so-called because animated films were based on drawings.