1. The act of attaching or the condition of being attached. 2. Something, such as a tie, band, or fastener, that attaches one thing to another. 3. A bond, as of affection or loyalty; fond regard. 4a. A supplementary part; an accessory: bought a vacuum cleaner with several attachments. See synonyms at appendage. b. A supplementary document that is attached to a primary document: stapled two attachments to the memorandum.5.Lawa. Legal seizure of property or a person. b. The writ ordering such a seizure.