Sudoku Terminology: Complete Glossary

Mastering Sudoku terminology is essential for understanding solving techniques, communicating with other players, and advancing your puzzle-solving skills. This comprehensive glossary covers all the important terms, techniques, and concepts used in Sudoku.

Basic Sudoku Terms

Grid and Structure

Grid

The 9×9 square containing all 81 cells of a Sudoku puzzle.

Cell

An individual square in the Sudoku grid that can contain one digit from 1 to 9.

Row

A horizontal line of 9 cells in the Sudoku grid.

Column

A vertical line of 9 cells in the Sudoku grid.

Box

A 3×3 subgrid containing 9 cells. Also called a "block" or "region."

House

Any row, column, or box in the Sudoku grid.

Given

A number that is pre-filled in the puzzle when you start solving.

Clue

Another term for a given number in the puzzle.

Solving Terms

Candidate

A possible digit that could go in a particular cell.

Pencil Mark

Small numbers written in the corners of cells to track possible candidates.

Elimination

The process of removing impossible candidates from a cell.

Placement

Filling in a digit in a cell after determining it's the only possibility.

Solution

The complete, correct filling of all 81 cells in the Sudoku grid.

Basic Solving Techniques

Single Techniques

Naked Single

A cell that has only one possible candidate remaining.

Hidden Single

A cell that is the only cell in a row, column, or box that can contain a specific digit.

Last Possible Number

Another term for a hidden single.

Pair Techniques

Naked Pair

Two cells in the same house that contain exactly the same two candidates.

Hidden Pair

Two cells in the same house that are the only cells that can contain two specific digits.

Locked Pair

Another term for a naked pair.

Triple Techniques

Naked Triple

Three cells in the same house that contain exactly the same three candidates.

Hidden Triple

Three cells in the same house that are the only cells that can contain three specific digits.

Locked Triple

Another term for a naked triple.

Intermediate Techniques

Pointing and Claiming

Pointing Pair

When a digit appears in only two cells of a box, and both cells are in the same row or column.

Pointing Triple

When a digit appears in only three cells of a box, and all three cells are in the same row or column.

Claiming

When a digit appears in only two or three cells of a row or column, and all those cells are in the same box.

Box/Line Reduction

Another term for pointing pair or claiming.

Basic Fish Patterns

X-Wing

A pattern where a digit appears in exactly two cells in two different rows (or columns), and these cells share exactly two columns (or rows).

Swordfish

A pattern where a digit appears in exactly two cells in three different rows (or columns), and these rows share exactly three columns (or rows).

Jellyfish

A pattern where a digit appears in exactly two cells in four different rows (or columns), and these rows share exactly four columns (or rows).

Advanced Techniques

Wing Patterns

Y-Wing

A pattern involving three cells with three candidates that can eliminate candidates from other cells.

XY-Wing

A variation of Y-Wing where the three cells have specific candidate relationships.

XYZ-Wing

An extended version of XY-Wing involving four cells.

W-Wing

A pattern that uses two cells with the same two candidates to eliminate candidates from other cells.

M-Wing

A pattern similar to W-Wing but with different candidate relationships.

Chain Techniques

Forcing Chain

A logical sequence that explores the consequences of placing a digit in a cell.

Alternating Inference Chain (AIC)

A chain of logical connections that alternates between strong and weak links.

Color Chain

A method of tracking alternating possibilities using two colors.

Multi-Color Chain

An extended version of color chaining using multiple colors.

Remote Pair

A chain of cells that alternate between two candidates.

Unique Rectangle Techniques

Unique Rectangle

A pattern of four cells that would create multiple solutions if not handled properly.

Type 1 Unique Rectangle

A unique rectangle where one cell has extra candidates.

Type 2 Unique Rectangle

A unique rectangle where two cells have extra candidates.

Type 3 Unique Rectangle

A unique rectangle with more complex candidate relationships.

Specialized Terms

Pattern Recognition

Skyscraper

A pattern that uses strong and weak links to eliminate candidates.

Two-String Kite

A pattern involving two cells connected by a common row and column.

Empty Rectangle

A pattern where a box has no candidates for a specific digit in a particular row or column.

Finned Fish

A fish pattern where one of the rows or columns has an extra candidate that breaks the perfect pattern.

Mathematical Concepts

45 Rule

The rule that each row, column, and box must sum to 45 (1+2+3+4+5+6+7+8+9).

Latin Square

The mathematical concept that Sudoku is based on, where each symbol appears exactly once in each row and column.

Constraint Satisfaction

The mathematical problem of finding values that satisfy all given constraints.

Backtracking

A solving algorithm that tries different possibilities and backtracks when they lead to contradictions.

Puzzle Creation Terms

Construction

Generator

A program or algorithm that creates Sudoku puzzles.

Validator

A program that checks if a Sudoku puzzle has a unique solution.

Difficulty Rating

A measure of how hard a puzzle is to solve, often based on the techniques required.

Symmetry

The arrangement of given numbers in a symmetrical pattern.

Minimal Puzzle

A puzzle with the minimum number of clues needed for a unique solution (17).

Quality Terms

Well-Constructed

A puzzle that can be solved using logical techniques without guessing.

Elegant

A puzzle that requires minimal clues and uses advanced techniques efficiently.

Fair

A puzzle that has a unique solution and can be solved logically.

Broken

A puzzle that has multiple solutions or no solution.

Competition and Speed Solving

Competition Terms

Tournament

An organized competition where players solve Sudoku puzzles for prizes or recognition.

Speed Solving

The practice of solving Sudoku puzzles as quickly as possible.

Time Attack

A competition format where players race to solve puzzles in the shortest time.

Accuracy

The percentage of puzzles solved correctly without errors.

Personal Best (PB)

A player's fastest time for solving a particular type of puzzle.

Performance Terms

Solve Time

The time taken to complete a Sudoku puzzle.

Average Time

The mean time taken to solve multiple puzzles.

Consistency

The ability to maintain similar solve times across multiple puzzles.

Streak

The number of consecutive puzzles solved correctly.

Technology and Software

Digital Terms

App

A mobile or desktop application for playing Sudoku.

Solver

A program that can solve Sudoku puzzles automatically.

Hint System

A feature in digital Sudoku that provides assistance to players.

Undo/Redo

Features that allow players to reverse or repeat their moves.

Auto-Fill

A feature that automatically fills in pencil marks for all possible candidates.

Interface Terms

Theme

The visual appearance and color scheme of a Sudoku interface.

Customization

Options to modify the appearance and behavior of a Sudoku app.

Statistics

Data tracking features that monitor solving performance and progress.

Achievement

Recognition for reaching certain milestones or completing challenges.

Common Abbreviations

AIC

Alternating Inference Chain

ALS

Almost Locked Set

BUG

Bivalue Universal Grave

UR

Unique Rectangle

XY

XY-Wing technique

XYZ

XYZ-Wing technique

Related Resources

Continue learning with these related articles:

• Best Solving Techniques - Learn how to apply these terms
• Sudoku FAQ - Get answers to common questions
• Difficulty Levels - Understand puzzle complexity