I was thinking about what a strange word 'comic' is. The implication, of course, is that it should be funny. 'Cartoon', also has that implication of humour, although less so, I think, than 'comic'. But obviously in many cases they are not intended to be funny, which makes me wonder why we don't have a word (correct me if I'm wrong) for the serious image. Obviously 'graphic novel' has allowed the 'comic book' to get away from the humour aspect, but to my knowledge there isn't a singular - a word for the single image conveying a message which is not humourous.