dvd as an abbreviation for Dasvidaniya, which in Russian means goodbye. Dasvidaniya is actually two words, not one: до (until) and свида́ния (meeting / date). So literally it means “until the next meeting“. Dasvidaniya is a formal way to say goodbye and should be used with people you don't know and those older than you.(Cribbed with Google's help from learnrussianwords.com.)

dvd removed files in Unix Version 6 and earlier. If memory serves, it operated directly on the file system data structures and was useful for recovering when the file system got "stuck".