Sudoku Terminology: 25 Common Terms Every Solver Should Know
A beginner-friendly guide to Sudoku terminology, including the most common grid, note-taking, and solving terms you will see in tutorials and strategy guides.
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The fastest way to learn Sudoku is to play an easy grid right away, then come back to the article when you get stuck.
Print an Easy Puzzle →If you have ever opened a Sudoku tutorial and felt lost by words like candidate, house, locked candidates, or conjugate pair, this guide is for you. This Sudoku terminology article explains the most common words solvers use so you can follow strategy guides, understand puzzle discussions, and make better decisions in your own grids.
Quick answer: Sudoku terminology is the shared vocabulary used to describe the grid, the starting clues, your notes, and the logical patterns used to solve puzzles. Once you understand the terms, it becomes much easier to read tutorials and spot what a technique is really asking you to look for.
Why Sudoku terminology matters
Sudoku is simple at the rules level, but the language around solving gets more specific as puzzles get harder. A beginner may know that every row, column, and 3×3 box must contain digits 1 through 9 exactly once. But once you start reading strategy content, you quickly run into new terms.
Learning Sudoku terminology helps you do three practical things:
- Understand tutorials without stopping every few lines.
- Recognize whether two different articles are talking about the same idea with slightly different wording.
- Build a cleaner mental checklist when you solve on paper or on screen.
Core grid terms in Sudoku terminology
1. Grid
The grid is the full 9×9 Sudoku puzzle. It contains 81 cells arranged into rows, columns, and boxes.
2. Cell
A cell is one individual square in the grid. A cell can contain either a given, a solved digit, or pencil marks.
3. Row
A row is a horizontal line of 9 cells. Every row must contain the digits 1 through 9 exactly once.
4. Column
A column is a vertical line of 9 cells. Like rows, columns must also contain the digits 1 through 9 exactly once.
5. Box
A box is one of the nine 3×3 regions in a standard Sudoku puzzle. Some players call it a block. Both words usually mean the same thing.
6. House
In Sudoku terminology, a house is any row, column, or box. If an article says a digit must appear once in every house, it means every row, every column, and every box.
7. Unit
Unit is often used as a synonym for house. Some authors prefer one word over the other, but in most beginner and intermediate material they mean the same thing.
8. Peer
A peer is any cell that shares a row, column, or box with another cell. If you place a 6 in one cell, every peer of that cell can no longer contain 6.
Starting clues and note-taking terms
9. Given
A given is a starting digit that is already printed in the puzzle before you begin. Givens do not change. If you want a deeper definition, see what a given means in Sudoku.
10. Clue
Clue is another common word for a given. In most Sudoku articles, given and clue are used interchangeably.
11. Digit
A digit is one of the numbers 1 through 9 used in the puzzle. Sudoku uses digits as symbols, not arithmetic values. You do not add or subtract them.
12. Candidate
A candidate is a possible digit for an unsolved cell. If a cell could still legally be 2, 5, or 9, those are its candidates. This is one of the most important Sudoku terminology terms because many solving techniques are really about removing candidates until one value remains.
13. Pencil mark
A pencil mark is a note you write inside a cell to track candidates. Digital apps may call these notes or notations.
14. Full notation
Full notation means you write all remaining candidates in unsolved cells. This gives you the most information, but it also creates more visual clutter.
15. Snyder notation
Snyder notation is a lighter note-taking system that usually records only candidates with special positional value, especially inside boxes. It is less noisy than full notation, but it takes practice to use well.
Common solving terms every player should know
16. Scan
To scan means to check rows, columns, and boxes in a deliberate pattern instead of staring randomly at the puzzle. Good scanning often finds easy placements before you need harder strategies.
17. Elimination
An elimination happens when logic proves that a candidate cannot go in a cell. Many Sudoku techniques do not place a digit immediately. They eliminate options first.
18. Placement
A placement is when you fill in a digit because only one value can legally remain in that cell or house.
19. Naked single
A naked single is a cell with only one remaining candidate. Because there is no alternative, that digit must be placed.
20. Hidden single
A hidden single is a digit that appears only once among the candidates in one row, column, or box. The cell may still show multiple notes, but that one digit has only one legal location in the house.
21. Pair, triple, and quad
These terms describe groups of two, three, or four digits tied together by logic. You will see them in patterns such as naked pairs, hidden triples, and hidden quads. The basic idea is that if a small set of digits is confined to a matching small set of cells, other candidates can often be removed.
22. Locked candidates
Locked candidates happen when a digit is restricted in a way that creates eliminations between a box and a row or column. This family includes pointing and claiming. If you already know the term but not the details, compare claiming Sudoku with box-line interactions.
23. Conjugate pair
A conjugate pair is two cells in the same house that contain the same candidate and no other cell in that house can take that digit. One of the two must be true, which makes conjugate pairs useful in chain-based logic.
24. Bivalue cell
A bivalue cell is a cell with exactly two candidates left. These cells are especially important in advanced chain techniques because each candidate creates a clean either-or relationship.
25. Contradiction
A contradiction is a logical impossibility reached after following an assumption. In strict logic solving, contradictions are used carefully to prove that one branch cannot be correct.
Sudoku terminology beginners often mix up
Given vs candidate
A given is fixed from the start. A candidate is only a possibility in an unsolved cell. Mixing these up causes a lot of confusion when reading tutorials.
House vs box
A box is only one type of house. A house can be a row, a column, or a box.
Naked single vs hidden single
A naked single is obvious from one cell. A hidden single is obvious only after comparing candidates across a full row, column, or box.
Placement vs elimination
A placement fills a digit. An elimination removes an option. Strong solvers do both, but many intermediate steps are eliminations first and placements second.
How to use Sudoku terminology while solving
You do not need to memorize every advanced term before you can improve. A more practical approach is to learn the vocabulary in layers:
- Master grid words first: row, column, box, house, cell, peer.
- Master note-taking words next: given, candidate, pencil mark, full notation.
- Then learn solving words in order: scan, elimination, naked single, hidden single, pair, locked candidates.
Once these terms feel natural, tutorials become much easier to follow. You stop translating every sentence and start seeing the logic on the board.
A quick example using real Sudoku terminology
Imagine a row where digit 4 can only appear in two cells, and both of those cells sit inside the same 3×3 box. That is a locked-candidates situation. Because the 4 must stay in that row inside that box, other cells in the same box can have 4 eliminated.
This example shows why vocabulary matters. If an article says, “Look for locked candidates created by a row-box interaction,” you can only act on that advice if terms like candidate, row, and box are already clear.
Sudoku terminology FAQ
What is the most important Sudoku terminology term for beginners?
Candidate is arguably the most important term because so many Sudoku strategies depend on understanding what digits are still possible in each unsolved cell.
Is a house the same as a box in Sudoku?
No. A box is one type of house. Rows and columns are also houses.
What is the difference between a clue and a given?
In standard Sudoku articles, there is usually no difference. Both words refer to the starting digits printed in the puzzle.
Do I need to learn advanced Sudoku terminology to solve easy puzzles?
No. Easy puzzles usually require only a few core terms such as row, column, box, candidate, and single. Advanced vocabulary becomes more useful as you move into harder grids and strategy guides.
Conclusion
Sudoku terminology is not just puzzle jargon. It is the language that makes strategy guides readable and solving steps easier to follow. If you understand words like given, candidate, house, and locked candidates, you will learn new techniques faster and make fewer mistakes when a puzzle gets harder.
If you want to keep building from here, read what a candidate means in Sudoku, review what a house is in Sudoku, and then move on to Sudoku order of operations to turn the vocabulary into a repeatable solving routine.