Sort of. It depends what context it is being used in. Gradually almost means that it is slow, but sure.
If the sentence is one like "The pumpkin grew gradually." The opposite would be "The pumpkin grew quickly."
The opposite would be sudden or abrupt, so the word could be quick, rapid, or swift.
The opposite of sudden is gradual.
Gradual
The opposite of abrupt could be gradual, slow, or incremental.Calm, kind, nice...
The opposite of abrupt could be gradual, slow, or incremental.Calm, kind, nice...
Sudden
the answer is Suddenly, all at once.
rapid Or possibly "steep."
The opposite of accelerando is ritardando. While accelerando indicates a gradual increase in tempo, ritardando refers to a gradual slowing down of the pace in music. Both terms are used to convey changes in speed, but they represent opposite effects in a piece's rhythm.
The opposite would be sudden or abrupt, so the adjective could be hurried or instant.
A five letter word that is the opposite of the word "gradual" and contains a second letter of "l" is a popular word game answer. The five letter word being sought is "fleet."
Fast, quick or speedy.