in large part; mainly or chiefly
"These accounts are largely inactive"
In a widespread or large manner.
"The new policy is largely affecting every department in the company."
In plain English: Largely means mostly or for the most part.
"The success of the project was largely due to the hard work of the entire team."
Usage: Use largely to mean that something happens in most cases or to a great extent, often replacing the word mostly. Avoid using it when you need to specify a precise quantity or a small degree.
Largely is formed by adding the suffix -ly to the word large. It entered English as an adverb meaning "to a great extent," directly reflecting its root adjective.