Is it conventional to provide topic related word definitions in a glossary?
Since your thesis is about  Rubik's cube a section where you establish cube vocabulary, complete with definitions and examples, is entirely appropriate.  You can duplicate some of that material in the glossary, but I suspect your readers won't need to refer to it often. I would not introduce abbreviations or acronyms for &quot;cubie&quot; and &quot;facelet&quot;.
The first time you introduce a standard algorithm like depth first search you explain how it works and note that you will abbreviate it as DFS. You put that in the glossary.