The word<unk>  comes from the Latin word<unk> us (clandestine, hidden, secret), referring to  "knowledge of the hidden".  In the medical sense it is used to refer to a structure or process that is hidden, e.g. an<unk>  bleed" may be one detected indirectly by the presence of otherwise unexplained anaemia.
Occult
Chronic 
Acute 
Grief
Male
Oncogenic
Malignant
Senile