Disclosure refers to making known of a fact which has remained unknown so far. For example, in many states it is required by law for seller of a property to disclose any latent defects in a property; this may include flooding problem, leaky roof, etc.
A person applying for a job which involves working closely with the elderly or children must disclose the fact if they have any criminal record. The law of disclosure is mainly governed by state laws which tend to vary from state to state.