Frequency: The word is one of the 3000 most common words in English.
1.
You use ~ to emphasize a quality that someone or something has, and to say that it is their most important or basic quality. (FORMAL)
It’s been believed for centuries that great writers, composers and scientists are ~ quite different from ordinary people...
Essentially, vines and grapes need water, heat and light.
= fundamentally
ADV: ADV with cl/group emphasis
2.
You use ~ to indicate that what you are saying is mainly true, although some parts of it are wrong or more complicated than has been stated. (FORMAL)
His analysis of urban use of agricultural land has been proved ~ correct...
Essentially, the West has only two options...
ADV: ADV with cl/group, ADV with v vagueness