Fire investigation is the process of examining the cause and origin of a fire. If you're looking for synonyms for this term, there are several you may consider. One is fire inquiry, which is another way of saying examining the cause of a fire. Another synonym is fire examination, which is more focused on the process of examining a fire to determine its origin and cause. Other possible synonyms include fire inspection, fire review, fire analysis, and fire exploration. Whichever term you choose, the goal remains the same - to determine what caused the fire and how it can be prevented in the future.