swift(noun, adjective, adverb) adjective1. moving very fast- a swift current- swift flight of an arrow- a swift runnerSimilar word(s): fast, fleet adverb1. (obsolete, poetic) Swiftly. noun1. a small bird that resembles a swallow and is noted for its rapid flightDefinition categories: animal2. common western lizard; seen on logs or rocksDefinition categories: animal