Life insurance terminology shouldn't be confusing. Here is the definition of concealment.
The deliberate hiding of or failure to disclose "material" information known to be relevant in the underwriting of an insurance policy.
For example, John tells his agent during the application process that he has never smoked when actually he did five years ago and has since quit. If the truth comes to light after the policy is in force, depending on how much time has passed the insurer has the right to cancel or modify the policy.