Words of the sword.

Plain carbon steels with about 0.45 and 0.60 percent carbon. Less hard than high carbon grades, they are tough and forgiving, and 1060 is a classic choice for cutting practice.

A high carbon steel with about 0.95 percent carbon. It hardens well, takes a keen edge and, when clay tempered, shows a true hamon.

A silicon alloyed spring steel with about 0.60 percent carbon. Prized for toughness: under stress it bends and returns rather than chipping or breaking.

Fine lines of hardened steel that run from the hamon down toward the edge. They form during the quench and are said to stop a chip from spreading along the edge.

A groove carved along the side of the blade. It lightens the sword while keeping it rigid, and makes the blade whistle as it cuts the air. Often wrongly called a blood groove.

A wooden sword, usually of oak, used to practice kata and partnered drills safely. Also called bokuto.

The part of the hamon that runs inside the kissaki. Its shape and its turn back toward the spine are studied closely when a blade is appraised.

A sharp movement that flicks the blade, symbolically shaking blood from it, after the final cut and before the sword returns to the scabbard.

A hamon of rounded, budding shapes said to resemble clove buds. One of the most admired patterns of the Bizen tradition.

A light oil, usually mineral or camellia, scented with clove. Applied in a very thin film, it protects the blade from rust and is renewed after handling.

The pair of a long and a short sword, katana and wakizashi, worn together. In the Edo period it was the mark of the samurai class.

In modern swords, a blade forge welded from layers of different steels, then etched to reveal a flowing pattern. A different method from traditional Japanese folding, though the two are often confused.

Hardening the edge more than the spine. The hard edge keeps its sharpness while the softer spine absorbs shock. On a katana it is done with clay, and it leaves the hamon.

Steel folded on itself and forge welded many times, building thousands of layers. With tamahagane it spreads the carbon evenly and drives out slag. The layers show as hada.

The metal collar at the guard end of the handle. It reinforces the tsuka and is made as a pair with the kashira.

The curve of the cutting edge within the kissaki. A full fukura gives a sturdier point, a flatter one a sharper point.

Two narrow parallel grooves running along the side of the blade, in place of a single wide bo-hi.

A hamon of regular, rounded peaks that repeat along the blade like a row of half circles.

The cutting edge of the blade, and the hardest steel of the sword.

The metal collar at the base of the blade. It wedges the sword in the mouth of the scabbard and holds the tsuba firmly in place.

The grain visible in the steel of a polished blade, born of folding. It can look like wood grain (itame), burl (mokume) or straight lines (masame).

A polishing style that whitens the area of the hamon with small finger stones, drawing a crisp, stylized outline. Most modern polishes use it.

The line of the hardened edge, seen as a pale pattern along the blade. It is shaped by the clay applied before the quench and revealed by polishing.

The broad flat side of the blade between the shinogi and the cutting edge. The hamon and much of the grain are seen here.

A blade shape with flat sides and no ridge line, common on tanto.

Small folded paper triangles set under the crossings of the ito. They raise each crossing and keep the diamond pattern crisp.

The art of drawing the sword, cutting and returning it to the scabbard in one continuous flow, practiced through solo kata.

An unsharpened practice sword for iaido, usually with an alloy blade. It has the weight and balance of a real sword, without a cutting edge.

A hada that looks like the grain of a plank of wood. The most common grain on Japanese blades.

The cord wrapped around the handle, in silk, cotton or leather. It gives the grip its texture and its color.

The surface of the blade between the hamon and the shinogi, where the grain of the steel is studied.

The turn back of the boshi, where the hamon in the point curves back toward the spine. Its length and shape are key points of appraisal.

The metal cap at the end of the handle. It closes the tsuka and is made as a pair with the fuchi.

A fixed sequence of movements, repeated until it becomes second nature. The way iaido and kenjutsu are taught.

A curved, single edged sword with a blade longer than about 60 cm, worn edge up through the belt. It became the main sword of the samurai from the 15th century.

The hard, high carbon outer jacket of a laminated blade. It wraps around a softer core.

The classical schools of Japanese swordsmanship, taught through partnered kata, often with bokken.

The point of the blade, set off from the body by the yokote. Small, medium or large, its size often reflects the period of the sword.

The mouth of the scabbard, named after the open mouth of a carp. The habaki fits snugly into it.

The end of the scabbard, often capped in horn or metal to protect it.

A short groove near the base of the blade, ending a little above the habaki.

The complete set of mountings of a sword: handle, guard, scabbard and fittings. A blade can be remounted in a new koshirae.

The small knob on the side of the scabbard through which the sageo passes.

The two small notches where the blade meets the tang, one on the edge side and one on the spine side. The habaki rests against them.

A blade made from a single piece of steel, with no lamination. With clay tempering it still gets a hard edge and a softer spine.

A hada of straight, parallel lines running along the blade, typical of the Yamato tradition.

The signature chiseled into the tang by the smith, sometimes with a date or a place.

The small peg, traditionally of bamboo, that locks the handle onto the tang. It should be checked before every use.

The hole through the tang, and through the handle, that the mekugi passes through.

Small ornaments set under the wrap on each side of the handle. They fill the palm and carry a motif.

Any irregular hamon, as opposed to a straight one. It wanders, peaks and breaks along the length of the blade.

A hada of rounded, swirling figures, like the burl of a tree.

A modern term for a blade made from one single steel, the same idea as maru. Simple, strong and easy to heat treat evenly.

The spine, the back of the blade opposite the edge.

The length of the blade, measured in a straight line from the tip to the notch on the spine where the tang begins.

The tang, the part of the blade hidden inside the handle. It carries the signature and the file marks of the smith.

Bright crystals of hardened steel large enough to be seen one by one, sparkling in and around the hamon.

Literally, Japanese sword. In the strict sense, a sword forged in Japan by a licensed smith from tamahagane, using traditional methods.

Crystals of hardened steel too fine to be seen one by one, forming a soft, misty line along the hamon.

A very long field sword, with a blade well beyond the length of a katana. Too long to be drawn from the belt in the usual way.

A hamon of slow, gentle waves, like a calm sea.

Returning the blade to the scabbard, calmly and without looking. The closing gesture of every kata.

A polishing step in which a fine iron compound is rubbed into the blade, darkening the steel so the grain and the hamon stand out.

Soft rice paper used to wipe old oil and powder from the blade, from the base toward the point, edge turned away from the hand.

Drawing the sword and cutting in a single motion. The first movement of most iaido kata.

The traditional cycle of heating, folding and forge welding the steel, repeated many times to refine it.

A sequence of stones, from coarse to very fine, used by the togishi. The last stages use thin finger stones called hazuya and jizuya.

The flat cord passed through the kurikata of the scabbard. It ties the sword to the belt and adds a line of color.

Ray skin wrapped around the wooden core of the handle, under the ito. Its rough surface keeps the wrap from slipping.

A laminated construction in which a hard steel edge is set between two softer side plates.

A traditional polish without whitening of the hamon. The temper line shows in its natural shape, quieter but truer to the steel.

The scabbard, carved from two halves of wood, usually magnolia, then lacquered. The blade rests inside without its edge touching the wood.

Thin metal washers set on each side of the tsuba. They take up any play and keep the guard tight.

The soft, low carbon core of a laminated blade. It absorbs shock so the hard outer steel does not crack.

A live sword with a sharpened edge, made for cutting, as opposed to an iaito or a bokken.

The ridge line that runs along each side of the blade, between the edge and the spine. It stiffens the blade.

The narrow flat surface between the shinogi and the spine.

The classic katana shape, with a ridge line along each side and a yokote marking off the point.

A plain mounting of unlacquered magnolia wood, used to store a blade at rest. The wood breathes and keeps moisture away from the steel.

The curvature of the blade, measured at its deepest point between the spine and a straight line drawn from tip to base.

A straight hamon running parallel to the edge. Sober, and difficult to make perfectly even.

A tool steel with about 1 percent carbon and a little tungsten. Very hard and resistant to wear, it holds its edge for a long time and shows a clear hamon when clay tempered.

The older long sword, more deeply curved, worn hanging from the belt with the edge down. It came before the katana and was made for the mounted warrior.

Jewel steel. The steel smelted from iron sand in a tatara, the traditional raw material of the nihonto.

Test cutting with a live blade, today on rolled and soaked tatami mats. It tests the sword and the technique alike.

A dagger with a blade shorter than about 30 cm, often in hira-zukuri shape.

A clay furnace in which iron sand and charcoal burn for about three days. Breaking it open reveals the bloom from which tamahagane is sorted.

The sword polisher. Over days or weeks, the togishi refines the geometry, sharpens the edge and reveals the hamon and the grain.

The guard between the handle and the blade. It protects the hand, balances the sword and is often its most decorated part.

Applying clay to the blade before the quench: a thin layer on the edge, a thicker one on the body. The pattern drawn in the clay becomes the hamon.

The handle: a wooden core covered in same and wrapped in ito, held to the tang by the mekugi.

The art of wrapping the handle. Hineri-maki, with twisted crossings, is the classic style. Tsumami-maki folds each crossing for a flatter, finer diamond.

A silk ball filled with very fine stone powder, dabbed on the blade to lift old oil. Use it sparingly: it is a gentle abrasive.

The companion sword, with a blade between about 30 and 60 cm. Worn with the katana, the pair forms the daisho.

The quench. The blade is heated evenly, then plunged into water. The edge hardens and the blade takes its curve.

The line that separates the point from the body of the blade on a shinogi-zukuri sword.