hidden

a secret intention or purpose behind someone's actions

a camera used to film people without their knowledge

a reason for doing something that is kept secret

a natural skill or ability that someone has but does not show

an interpretation or significance that is not immediately obvious

an unexpected expense that is not included in the basic price

a risk or threat that is not easily seen or recognized

a piece of information or an idea that is conveyed in a subtle way

a microphone used to listen to people without their knowledge

a secret area for storing things inside a larger object

a likely mistake or problem in a situation that is not obvious at first

a secret corridor or route

an additional charge that is not apparent at first

something that can be a source of danger that is not visible

complex or serious aspects of someone's character that are not obvious