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Shape shifting, in language terms, has nothing to do with metamorphosing oneself into a different shape, as it would do in science fiction movies. But it is an interesting concept and one that any person new to a language will need to get a hold on. In all languages, words can shift their shape, depending on many factors. One word, for example, to write, can then be turned into lots of different words - wrote, writes, written, writer. Or even simple nouns, such as house, can be changed to houses, and even houseful. In this way, the same stem of the word takes on a slightly different meaning. The basic idea remains the same, but the word changes depending on who is doing it, what is being done to it, how many there are, when it was done. This is shape shifting.