shadowy
adj.adj. full of shadows or dark. You can also use it to describe people or groups that are mysterious and keep their activities secret.
adj. characterised by darkness or gloom; lacking clear definition. Often used figuratively to describe individuals or organisations that operate in secrecy or outside of public scrutiny.
A shadowy figure stood at the end of the dark hallway.
The investigation revealed that a shadowy group of investors had been controlling the company's decisions from behind the scenes.
The novel is set in the shadowy underworld of 1940s espionage, where loyalties are fluid and every character seems to be hiding a dangerous secret.
From Middle English schadwy, schadowy, equivalent to shadow + -y.
Often used both literally to describe lighting and figuratively to describe a lack of transparency.