"Origins of words" by Susie Dent, Countdown 18/10/17 (spitting image)

I had an e-mail from Jen Dalton, so thanks to Jen, she asked where spitting image comes from because she's often told that she's the spitting image of her sister. It's evolved through various incarnation over the centuries so it's pretty old, this one, but they all convey the idea of an exact likeness to someone or something else. First emerged in the early 1800s, because people would describe a child particularly as the spit of their mother or father. In other words, they looked so identical it's almost as though they've been spat directly out of their parents' mouth. A very direct image, if you like, a little bit crude, maybe. And a little later, this idea of spit was combined with image, that's just for added emphasis. So there was a Victorian romance, for example, which goes, "She's just like the poor lady that's dead and gone, the spit and image she is". And that same phrase, spit and image, if you said it very quickly, it sounds a little bit like spitten image and spitten was the old past tense of spit. So today we say spat, but in the olden days it was spitten. And that in turn was then misheard as spitting, so it's basically sort of trips of the ear, if you like, we hear something and then we register that in writing and that's, of course, where the expression remains today. But it was literally as though somebody has been spat out of somebody else's mouth,  and I hope that answers Jen's question. Spitting image was ones spitten image.