- Fine-grained, dense sedimentary rock consisting of interlocking crystals of quartz approximately 30 microns in diameter. Chert and its varieties, such as flint, are non-gem varieties of cryptocrystalline-granular quartz. These stones chip very easily and thus may be fashioned into tools with a sharp edge; they are also used for building.
- Cutting instruments consisting of a blade with a sharpened longitudinal edge fixed in a handle, either rigidly as in a table-, carving, or sheath-knife, or with a joint as in a pocket- or clasp-knife. Knives may be used to cut food, especially in serving and eating, as weapons, and for other purposes. The blade may be of steel or another metal or stone, as in the flint knives of early man, or of another material such as ivory or wood (as with a paperknife). The term also refers to tools that are shaped or used as knives, even if the edge is not particularly sharp or actually used for cutting.
- Refers to the cultures of the continent of North America, which is bounded by the Atlantic Ocean, the Pacific Ocean, the Arctic Circle, and Central America. In classifications schemes based on physical geography, Central America, and North America are parts of the same continent.