Knife

: knives; from Old Norse knifr 'knife, dirk'[1]) is a tool or weapon with a cutting edge or blade, usually attached to a handle or hilt.

There is also the enterçado construction method present in antique knives from Brazil, such as the Sorocaban Knife, which consists in riveting a repurposed blade to the ricasso of a bladeless handle.

Stainless steel is an alloy of iron, chromium, possibly nickel, and molybdenum, with only a small amount of carbon.

High carbon stainless steel blades do not discolor or stain, and maintain a sharp edge.

Forged blades are made by heating a single piece of steel, then shaping the metal while hot using a hammer or press.

Flat ground blades have a profile that tapers from the thick spine to the sharp edge in a straight or convex line.

The "wave" feature is another prominent design, which uses a part of the blade that protrudes outward to catch on one's pocket as it is drawn, thus opening the blade; this was patented by Ernest Emerson and is not only used on many of the Emerson knives, but also on knives produced by several other manufacturers, notably Spyderco and Cold Steel.

[17] Automatic or switchblade knives open using the stored energy from a spring that is released when the user presses a button or lever or other actuator built into the handle of the knife.

[18] Increasingly common are assisted opening knives which use springs to propel the blade once the user has moved it past a certain angle.

[19] In the lock back, as in many folding knives, a stop pin acting on the top (or behind) the blade prevents it from rotating clockwise.

To disengage, this leaf spring is pushed so it again rests flush against the handle allowing the knife to rotate.

One method of opening is where the blade exits out the front of the handle point-first and then is locked into place (an example of this is the gravity knife).

Another form is an OTF (out-the-front) switchblade, which only requires the push of a button or spring to cause the blade to slide out of the handle and lock into place.

To retract the blade back into the handle, a release lever or button, usually the same control as to open, is pressed.

More exotic materials usually only seen on art or ceremonial knives include: Stone, bone, mammoth tooth, mammoth ivory, oosik (walrus penis bone), walrus tusk, antler (often called stag in a knife context), sheep horn, buffalo horn, teeth, and mop (mother of pearl or "pearl").

For example, knife handles may be made thicker or with more cushioning for people with arthritis in their hands.

For example: A primary aspect of the knife as a tool includes dining, used either in food preparation or as cutlery.

[3] Knife symbols can be found in various cultures to symbolize all stages of life; for example, a knife placed under the bed while giving birth is said to ease the pain, or, stuck into the headboard of a cradle, to protect the baby;[citation needed] knives were included in some Anglo-Saxon burial rites, so the dead would not be defenseless in the next world.

[21][22] The knife plays an important role in some initiation rites, and many cultures perform rituals with a variety of knives, including the ceremonial sacrifices of animals.

[23] Samurai warriors, as part of bushido, could perform ritual suicide, or seppuku, with a tantō, a common Japanese knife.

[citation needed] As early as 1646 reference is made to a superstition of laying a knife across another piece of cutlery being a sign of witchcraft.

Large knife with polished wooden handle, close to a leather sheath
A Bowie knife of pattern-welded steel
Different parts of a knife indicated with numerals
Characteristic parts of a knife
A Gerber -made full- tang survival knife. The metal from the blade extends into the handle.
Morakniv carbon steel knife
Seated female workers making knives on machinery with large spinning drums
Knife blade mass production
Knife blades have different profiles
Fixed-blade knife with wooden handle on a table, next to a molded plastic sheath
cKc pen knife
Folding pocket knife with multiple exposed tools
A Swiss Army knife
Close-up of the pivot joint of a folding knife, showing locking barrel inserted through holes in the handle
The Benchmade Axis Lock mechanism
An OTF knife, showing the sliding blade being extended from the handle
Minsk folding knife with articulated frame grip
A traditional knife handle made from buffalo horn ( Tasikmalaya , Indonesia)
Birchbark knife handle
A large traditional Tuareg knife
Knife from the stone age, Nok , Nigeria
Table knives
A butter knife (on the left) is used to spread butter, while a kitchen knife (on the right) is sharp enough to slice a carrot.
Western
Diver's knife from Three bolt equipment
Knives for cutting cheese
A Head knife (Round knife).
A simple letter opener, or paper knife
Painting of an elderly man holding a young boy's head down with one hand; a winged angel restrains the man's other hand, which grasps a knife. A ram looks on from the side; in the background is a Renaissance landscape with hills, trees, and a castle.
The Sacrifice of Isaac by Caravaggio , (1590–1610; Oil on canvas; Uffizi ). Abraham is holding the sacrificial knife.
A man sharpening a knife in Nepal using a traditional method