Largely means for the most part. Largely unchanged, largely due to the weather, largely ignored.
It admits exceptions without naming them, which is what makes it useful and what makes it worth watching: largely unchanged means something changed. It is a hedge, and careful writing says how much rather than leaving the word to do it.
1adverblargelyFor the most part.
“The town was largely destroyed in the war, but the old church survived.”
largely is a degree.
From large + -ly.
Etymology from Wiktionary, CC BY-SA