Investigation is a broad term that encompasses many different activities. DIAGNOSIS is a nine-letter word meaning the process of identifying the cause of a disease or injury. An AUDIT is a five-letter word meaning an official EXAMINATION of an organization's financial records. DELVING is a seven-letter word meaning to SEARCH deeply into something. INQUISITION is an eleven-letter word meaning an official investigation, especially one of a political or religious nature. OBSERVATION is an eleven-letter word meaning the action or process of closely observing or monitoring something. EXAMINATION is an eleven-letter word meaning the action of examining something closely. TRIAL is a five-letter word meaning a formal INQUIRY to decide a disputed issue. HUNT is a four-letter word meaning to SEARCH for something. CASE is a four-letter word meaning a particular instance of a person or thing. PROBE is a five-letter word meaning to make a detailed SEARCH for information. SEARCH is a six-letter word meaning to look or seek thoroughly. INQUIRY is a seven-letter word meaning a formal request for information. RESEARCH is an eight-letter word meaning the systematic investigation into and study of materials and sources in order to establish facts and reach new conclusions.