awake
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."
The word is "awake" or as an alternative, "alert" (as opposed to sleepy).
A five letter word for the opposite of lower is upper.
A five letter word meaning the opposite of hurry would be dally. There may well be others
least
night
giant
plain
fresh
Happy.
Sharp
small