Sudoku is an abbreviation of the Japanese phrase sūji wa dokushin ni kagiru (数字は独身に限る), which translates as "the digits must remain single" or "the digits are limited to one occurrence." The name is a direct description of the game's single rule: each digit may appear only once in every row, column, and 3×3 box. Today it is a globally popular logic puzzle played on 9×9 grids in newspapers, books and apps worldwide.
Breaking Down the Word Sudoku
The name is built from two Japanese elements, written with two kanji characters, 数独:
- Sū (数) — means "number" or "digit."
- Doku (独) — means "single" or "alone."
Together they compress the longer phrase suuji wa dokushin ni kagiru — "the numbers must remain single" — into a punchy two-syllable name. In Japanese, dokushin (独身) literally means an "unmarried person," which is why some translations render the phrase as "the digits must stay single, like a bachelor" (Wikipedia; Dictionary.com).
The pronunciation that caught on worldwide is "soo-DOH-koo," following the Japanese reading of the kanji.
Where the Name Came From: A Short History
Despite its Japanese name, sudoku did not originate in Japan. The puzzle's journey spans three countries:
1979 — United States. The modern puzzle was most likely designed by Howard Garns, a retired architect from Connersville, Indiana, and first published by Dell Magazines under the name "Number Place" (Wikipedia). It appeared in Dell Pencil Puzzles and Word Games.
1984 — Japan. Maki Kaji, president of the Japanese puzzle company Nikoli, discovered the puzzle and introduced it in Monthly Nikolist under its full Japanese title, Sūji wa dokushin ni kagiru. Kaji then coined the abbreviated name "Sudoku" by taking the first kanji of each compound word. Nikoli claims trademark rights to the name in Japan; some Japanese publishers still use "Number Place" or "Nanpure" instead (Wikipedia).
2004 — United Kingdom. The Times of London began publishing sudoku in November 2004 — after retired Hong Kong judge Wayne Gould, who had spent six years writing a computer program to generate the puzzles, persuaded the paper to run them (Wikipedia) — and the puzzle exploded worldwide within months — under the Japanese name Kaji had coined twenty years earlier.
So the puzzle is American in design, Japanese in name, and British in its launch to global fame.
The Deeper Roots: Latin Squares
The mathematical ancestor of sudoku is the Latin square, developed by the Swiss mathematician Leonhard Euler in the 18th century — a grid in which each symbol appears exactly once per row and column. Similar number puzzles also appeared in French newspapers in the 1890s. Howard Garns added the 3×3 box constraint that makes modern sudoku what it is (ResearchGate, "Properties of Sudoku Puzzles").
What the Name Tells You About the Rules
The meaning of the name is essentially the rulebook in two syllables. This number puzzle — a pure logic puzzle despite its digits — starts from a partially filled grid — the pre-filled numbers are called givens — and must ensure:
- Each row must contain the digits 1–9 exactly once — the digits remain single.
- Each column must contain the digits 1–9 exactly once.
- Each 3×3 box must contain the digits 1–9 exactly once.
No arithmetic is involved. As one academic paper on the puzzle notes, "the numerals in Sudoku puzzles are used for convenience; arithmetic relationships between numerals are absolutely irrelevant. Any set of distinct symbols will do" (Leiden University, "Creating and solving sudokus"). Letters, shapes, or colours would work identically — the name only demands that each symbol stays single.
Sudoku Variant Names and Their Meanings
The "doku = single" element lives on in the names of sudoku variants:
| Variant | Name meaning |
|---|---|
| Shidoku | Shi (four) + doku — 4×4 grid |
| Godoku | Go (five) + doku — 5×5 grid |
| Sudoku | The original 9×9 |
| Killer Sudoku | Adds "cages" with sums (English name, same single rule) |
More "Doku" Puzzles: The Naming Tradition
The Japanese naming tradition inspired a whole family of puzzle names. Wordoku (also called "word sudoku") swaps the digits 1–9 for nine letters, so the puzzle's name blends "word" with the familiar -doku ending — the "remain single" rule is identical, applied to letters instead of numbers. Jigsaw sudoku (irregular sudoku) keeps the 9×9 grid but replaces the neat 3×3 boxes with irregularly shaped regions, so it takes an English descriptive name rather than a Japanese one. Mini sudoku uses a 6×6 grid with 2×3 boxes for a quicker solve, while Samurai sudoku combines five overlapping 9×9 grids into one giant puzzle.
The most famous relative is Killer Sudoku, which keeps the single-occurrence rule but adds dotted "cages" where the digits must also sum to a given total — here the "killer" is English marketing, not Japanese etymology. If you want to try the original grids that made the name famous, our guide to choosing the right sudoku puzzle book covers difficulty levels and formats, and the sudoku puzzle books roundup compares popular collections.
Common Misconceptions
Sudoku is not a Japanese invention. The name is Japanese, but the puzzle was designed by an American and first published in New York.
Sudoku is not a math game. The digits could be replaced with letters or symbols without changing anything. It is a logic puzzle, and its name describes a logic constraint, not arithmetic.
Sudoku is not related to "sodoku." As Dictionary.com points out, sodoku is an entirely different word — a bacterial disease also known as rat-bite fever. The puzzle and the pathogen share nothing but a few letters.
What does sudoku literally mean?
Sudoku is short for the Japanese phrase *suuji wa dokushin ni kagiru*, meaning “the digits must remain single” — a description of the rule that each digit appears only once per row, column, and box.
What language is the word sudoku from?
Japanese. It was coined in 1984 by Maki Kaji of the puzzle company Nikoli as an abbreviation of a longer Japanese phrase.
Who invented sudoku?
The modern puzzle was most likely created by American Howard Garns and first published as “Number Place” by Dell Magazines in 1979. Maki Kaji gave it the name sudoku in Japan in 1984.
Why is it called sudoku if it was invented in America?
Maki Kaji, who introduced the puzzle to Japan, coined the Japanese name, and it was under that name that the puzzle became a global phenomenon after The Times of London adopted it in 2004.
What do the kanji in sudoku mean?
数独 combines 数 (*sū*, number) and 独 (*doku*, single/alone) — literally “number-single.”
Is sudoku a math puzzle?
No. It is a logic puzzle. The digits are just convenient symbols; arithmetic plays no role, which is exactly what the name’s “digits must remain single” rule describes.
What is the difference between sudoku and Number Place?
Nothing — Number Place was the puzzle’s original 1979 American name. Sudoku is the Japanese name that replaced it worldwide.
How do you pronounce sudoku?
“soo-DOH-koo,” following the Japanese reading of the kanji characters.
Where can I play sudoku online?
Free online sudoku is easy to find: MSN Sudoku ([zone.msn.com](https://zone.msn.com), Microsoft’s casual-gaming hub), Arkadium’s daily sudoku, and the puzzle packs on GridPuzzle all run in the browser with no sign-up. For printed collections, our guide to choosing a [sudoku puzzle book](https://plusword.co.uk/sudoku-puzzle-book/) rounds up the best volumes, from easy grids to extreme challenges.
Why do some Japanese publishers say “Number Place” instead of sudoku?
Nikoli claims trademark rights to the name “sudoku” in Japan, so some Japanese publishers use the original American name “Number Place” — or its Japanese rendering “Nanpure” — to avoid the trademark.
Does sudoku appear in dictionaries?
Yes. The word entered mainstream English dictionaries in the mid-2000s as the puzzle’s popularity exploded, and it is now listed as a noun meaning a logic puzzle in which digits must appear once per row, column and box.