The Free Dictionary defines apocope as a noun, meaning the loss of one or more sounds from the end of a word. They give the example of the modern English word sing being derived from Middle English singen. (Hoping to make a weak joke, I looked up dancen, to no avail. I did find that tappen is a Middle English word, which has suffered apocope in its present form, tap.)
I like the sound of this word more than anything. Apocope, apostrophe, apocalypse, apoplexy, apotheosis... hippopotamus.