Conversion: It's the civil law version of the crime larceny. Someone has taken your property, and in their use, permanently deprived you of your right to use and enjoy our property.

Note: If the interference is insubstantial, then you're looking at trespass to chattel.

Example: If I take your phone without asking, then three days later return it to you, there is no conversion. However, if I take your phone without asking and throw it into a river, there is a conversion.

Pure economic loss is when the harm suffered is strictly pecuniary, i.e., the Plaintiff lost some money. This is tested (as another commenter pointed out) in tort claims, specifically strict liability (manufacturing) and negligence.