The content found within an Oxford English Dictionary (OED) A to Z PDF generally spans 600,000 words
Depending on your level, different Oxford resources are available in digital or downloadable formats:
If you are looking for older or historical editions for research, digital archives host scanned versions of the full volumes: Internet Archive - OED All Volumes
: Unlike standard dictionaries that focus only on modern meanings, the OED provides the entire history of a word , often dating back to the 11th century.
: A thematic dictionary depicting essential vocabulary for survival and general communication. Oxford Learner's Dictionaries Specialized Oxford A–Z PDF Dictionaries Oxford Dictionary of Idioms
Español 
English 
Deutsch 
Italiano 
Français 
Nederlands 
Suomi 
Norsk bokmål 
Svenska 
Dansk