Cemetry for Cemetery is a classic case of a dropped vowel at the end of a common multisyllabic word. It can be found on the C, or moderate probability, list in our compilation of OPAC typos at
http://faculty.quinnipiac.edu/libraries/tballard/typoscomplete.html. Four months ago, the typo Cemetary appeared in these pages. Cemetary is a very different sort of a typo because many people don't know how to spell this word, whereas Cemetry is simply a case of carelessness.