To dream of a chainsaw represents wanton, complete disregard for feelings, no remorse, or little concern for consequences. A chainsaw may also reflect total insensitivity to others feelings. Uncaring forcefulness.
A chainsaw used by someone else to harm you or scare you symbolizes your feelings about some issue in your life that’s completely insensitive to your feelings, wishes, or life situation.
Example: A man dreamed of seeing a scary looking man with a chainsaw. In waking life his business partner totally screwed him over and left him with nothing as though it didn’t even matter.