adjective · indicates that something happened or existed a long time ago; already for a long time.

他早已知道了这个秘密。

adjective · formerly or previously (dialectal usage)

他早已在老家当过老师，所以对教学很有经验。

adjective · indicates that something has occurred a long time ago, emphasizing the duration of the state since the occurrence.

这种老掉牙的理论早已被现代科学推翻了。

adjective · for a long time or long ago

真相早已大白，你现在再怎么解释也没有用了。