What does attachment mean? Noun The act or process of (physically or figuratively) attaching. A strong bonding towards or with. A dependence, especially a strong one. A device attached to a piece of equipment or a tool. The means by which something is physically attached. (computing) A file sent along with an email. (law) Taking a person's property to satisfy a court-ordered debt. (meteorology) The act or process by which any (downward) leader connects to any available (upward) streamer in a lightning flash., advertising style