Secret
Part of speech: noun
Definition: Knowledge that is hidden and intended to be kept hidden.
Part of speech: verb
Definition: To make or keep secret.
Part of speech: adjective
Definition: Being or kept hidden.
Example sentence: The secret to success is to offend the greatest number of people.
Secluded
Part of speech: adjective
Definition: hidden, isolated, remote
Part of speech: verb
Definition: To shut off or keep apart, as from company, society, etc.; withdraw (oneself) from society or into solitude.
Example sentence: In my deepest troubles, I frequently would wrench myself from the persons around me and retire to some secluded part of our noble forests.