Formal:
* Omniscient: This is the most common and literal synonym, meaning "having infinite knowledge."
* All-knowing: This is a simpler and more direct way to say "knowing everything."
* Panoramic: This suggests a broad and comprehensive understanding of a particular subject.
* Encyclopedic: This implies a vast and detailed knowledge, like that found in an encyclopedia.
Informal:
* Wise: This suggests deep understanding and insight, gained through experience and reflection.
* Savvy: This implies a practical and intuitive understanding of a situation.
* Astute: This suggests keen intelligence and a sharp understanding of people and events.
* Know-it-all: This is a negative term, suggesting someone who acts like they know everything but is actually arrogant and ignorant.
Ultimately, the best word to use depends on the specific context and the intended meaning.