Origin: Latin prefix sub-
Substantially has 3 different meanings across 1 category:
to a great extent or degree
"I'm afraid the film was well over budget"
"painting the room white made it seem considerably (or substantially) larger"
"the house has fallen considerably in value"
"the price went up substantially"
In a strong substantial manner; considerably.
"The company's profits increased substantially after launching their new product line."
In plain English: Substantially means happening to a very great degree or amount.
"The new policy will substantially reduce carbon emissions by next year."
Usage: Use substantially to indicate that something has changed significantly or increased by a large amount, rather than slightly. It is often confused with similarly sounding words like essentially, but it specifically refers to degree and magnitude of difference.
The word substantially comes from combining the adjective substantial with the suffix -ly to form an adverb. It entered English by attaching a common grammatical ending to describe something done in a significant or meaningful way.