Unfortunately there isn't a clear name for it. There's a bunch of sibling comments that, I think, don't quite get it right. Autocomplete is a feature. For any given autocomplete implementation, there can be a number of different sources to actually populate the AC UI. Company mode in Emacs (COMPlete ANYthing) works this way - it's a general AC framework, and different modes can provide different AC sources to it. Hippie completion, in Emacs at least, refers to a combination of a variety of sources - text in the current buffer, in other buffers, on the kill ring (e.g. Recently copied text), etc.