- The class of vertebrate animals that are typically bipedal and warm-blooded, lay large-yolked hardshelled eggs, often arboreal, and possessing feathers, hollow bones, forelimbs adapted for flight (although some have lost the ability to fly) and hindlimbs for perching and locomotion, a four-chambered heart, keen vision, a horny beak without teeth, and a large muscular stomach. Birds arose from theropod dinosaurs, which were an order of carnivorous dinosaurs.
- Creating marks on the surface of a hard material, such as metal or glass, by incising with a sharp tool, when the designs or images created are for their own sake and not to be printed from. For printing processes that involve this technique plus intaglio printing from the surface, use "engraving (printing process)."
- Prints on paper incorporating impressions of a reverse design created on a printing plate, usually copper, into which the design has been incised (engraved) using burins or gravers. Historically, "engravings" has sometimes been incorrectly used to refer to all prints, regardless of the specific technique. For prints made from designs engraved on a flat wooden block, use "wood cuts"; for prints made from a plate that is etched rather than engraved, use "etchings."