Stealthy , stealthily ,ninja
The word for looking at someone or something secretly is "spying" or "peeking".
The word you are looking for is "conspire". It means to plan something secretly with others.
No secretly s an adverb, secret can be an adjective eg She has a secret friend
Secretly is an adverb. It modifies verbs by providing information on how an action is performed.
infatuated?
Covertly
The root word of "slowly" is "slow."
talk quietly talk slowly talk fluently talk clearly talk loudly talk openly talk secretly This is not all there must be many more
If by secretly you meant cautiously then walking stealthily or tip toeing .
secretly
Peep.
secretly talk