From the specification on the product page

The glossary

Japanese words and trade terms you will meet with us, briefly explained.

Steel

Aogami: Blue paper steel. Carbon steel with chromium and tungsten, in grades 1, 2 and Super.
Shirogami: White paper steel. A pure carbon steel, in grades 1, 2 and 3.
Ginsan: Silver 3. Stainless steel that sharpens almost like carbon steel.
VG10: Stainless steel from Takefu Special Steel, made for kitchen knives.
SG2 and R2: The same stainless powder steel under two names.
Powder steel: Steel made from metal powder pressed together under high pressure. Even and hard, but slower to sharpen.
Carbon steel: Steel that is easy to sharpen, but rusts if it is left wet.
Stainless steel: Steel with enough chromium that it does not rust in normal use.
HRC: Hardness measured on the Rockwell scale. A higher number means harder steel.
Patina: A dark, mottled film on carbon steel after use. It protects the steel.

San mai: Three layers: a hard core between two layers of softer steel.
Hagane: The hard core steel that forms the edge.
Jigane: The softer steel around the core.
Warikomi: The soft steel is split, and the core is laid in before they are forged together.
Honyaki: A knife from a single piece of steel, hardened hard at the edge and softer at the spine.
Hamon: The wavy line between the hard edge and the soft spine on a honyaki.
Double-bevel, 50/50: Sharpened on both sides. 50/50 means sharpened equally on both.
Single-bevel: Sharpened on one side. The back is flat or slightly hollow, and the knife is made for the right or the left hand.
Urasuki: The hollow back of a single-bevel knife.
Distal taper: The blade gets thinner from the handle towards the tip.
Shinogi: The line on the blade where the angle changes and the bevel begins.
Choil: The unsharpened rear part of the blade, by the handle.
Tang: The steel that runs from the blade into the handle.
K-tip: An angled, dropped tip, as on kiritsuke and bunka.

Kurouchi: Black surface. The scale from the forge is left on the blade.
Nashiji: A rough surface that looks like the skin of a nashi pear.
Tsuchime: Hammered surface with small dimples.
Kasumi: Mist. A matt, hazy surface.
Migaki: Polished, from matt to almost mirror bright.
Damascus: Layers of different steels, forged and folded so a pattern forms on the blade.

Gyuto: Cow sword. The Japanese chef’s knife.
Santoku: Three uses. A shorter all-round knife with a flatter edge.
Bunka: Culture. An all-round knife with an angled, pointed tip.
Kiritsuke: Knife with a k-tip. Traditionally single-bevel, today mostly double-bevel.
Nakiri: Vegetable cutter. Double-bevel, with a straight edge.
Usuba: Thin blade. Single-bevel vegetable knife.
Petty: A small knife used alongside the main knife.
Sujihiki: A long, double-bevel knife for meat and fish.
Yanagiba: Willow leaf. A long, single-bevel knife for sashimi.
Deba: A heavy fish knife, usually single-bevel.
Honesuki: A small, stiff boning knife for poultry.
Funayuki: Boat knife for fishermen, common in Tosa.

Wa handle: Japanese wooden handle. Light, and easy to replace.
Yo handle: Western handle, with two scales riveted to the tang.
Ferrule: The ring closest to the blade on a wa handle, often in horn or dark wood.
Pakkawood: Veneer pressed together with resin. Tolerates water and needs little care.
Saya: Wooden blade cover.

Burr: The thin edge that folds over to the other side when you have sharpened all the way out to the edge.
Grit: The number on the whetstone. A higher number is finer.
Nagura: A small stone that raises slurry on the whetstone.
Strop: A leather strap that straightens and polishes the edge without removing steel.
Thinning: The blade is ground thinner behind the edge once the core has worn down.
Tennen toishi: Natural whetstone.
Hamono: Edged tools. Part of the name of many knife workshops.
Tonya: Wholesaler. In Sakai the wholesaler orders the knives and fits the handles.
Dentoukougeishi: Official title for a traditional master craftsman.