It's a popular Japanese math game commonly found in newspapers and publications with related games (crosswords, etc.)

On online message boards, particularly 4chan's /v/, people mix the word for Japanese ritual suicide, "seppuku," with "sudoku." The typo has since spread and became adopted in a similar fashion to "pwn" in regards to "own."

A Sudoku is a japanese math puzzle consisting of 9 3X3 squares, each with 9 smaller squares inside. Once completed, the sudoku must have the numbers from one to nine appear once in each row, coloum and 3X3 square.

Ancient Japanese form of ritualistic suicide when they are dishonored, most commonly by sword.

the process of breaking an anal and mental sweat while in a public or private lavatory

A puzzle invented by an American but popularized by the Japanese.

The puzzle consists of a 9x9 grid which is partitioned into nine 3x3 boxes. Typically, 20 to 25 of the 81 cells are pre-filled with one numerical digit. The objective is to fill the remaining cells such that each digit (1 through 9) is represented in every row, column and box.

Easy to moderate puzzles can be solved via simple elimination.

More difficult puzzles require some "what if" propositions to solve.

Solving Sudoku by hand is a routine diversion but writing a program to solve or create Sudoku puzzles is a more interesting challenge.

an extremely addicting game. its kind of like pringles. once you start, you just can't stop. there's a whole table for it at barnes and nobles. you should go with your friends and pitch in and buy a book. you will fall in love.

as of right now, the current world chamption Su Doku player is a girl named Keira, but 2 others, Pauline and Alissa, are a close second and third.

A very complex number puzzle