Definition is so inconsistent within the community and has changed over the years. Currently, the below is generally agreed upon:

Full Set - All card numbers including secrets

Complete Set - All cards obtainable in packs (including reverse holos)

Master Set - Complete set along with deck exclusives and others, basically all card variations that have the set symbol

It gets confusing and inconsistent because by that definition, a master base set would include 4 print variations, a master jungle set would include 1st ed and unltd along with no jungle symbol errors, etc. But then what about error cards? Are those included or not? What about gen 6 when alt art promos were released? What about league promos?