Getting a glossary item to show when mouseover
No, as far as the computer is concerned, removing the apostrophe changes the word to four letters.
If you want to be syntactically correct AND show the definition - do something like...
"He ran [[ACC]]s..." or "He ran [http://scientolipedia.org/info/ACC ACC's]..."
Which will give either
This "He ran ACCs..."
This "He ran ACC's..."
OR - you could create a new glossary item for "ACCs" (with the same definition as for "ACC") and the mouse-over will work for when that is used.