Puzzle glossary
The words used in puzzle rules and solver explanations, in plain English.
- Anchor cell
- In Magic Difference and Magic Division, the first cell of a row or column, which you subtract from or divide from in turn.
- Block
- In a nonogram, a run of shaded cells whose length is given by a clue number.
- Box
- In Sudoku, one of the outlined sub-grids (3×3 on a 9×9 grid) that must hold each digit once.
- Cage
- A group of cells outlined together with a total (Killer Sudoku) or a target and operation (Calcudoku).
- Candidate
- A digit that is still possible in a cell. Candidates are often written small as pencil marks.
- Clue
- A given number in the grid — a cage total, a Kakuro sum, a Nurikabe island size or a nonogram line clue.
- Compartment
- In straights puzzles, an unbroken run of white cells that must hold consecutive digits.
- Given
- A digit printed in the puzzle at the start. It cannot be changed.
- A digit with only one possible cell in a row, column or box.
- Island
- In Nurikabe, a group of unshaded cells containing exactly one number, equal to its size.
- Latin square
- An N×N grid where each of N symbols appears once in every row and column — the base of Sudoku, Calcudoku and Futoshiki.
- Misère
- A version of a game where the player who makes the last move loses, as in misère Nim.
- Naked single
- A cell with only one candidate left.
- Nim-sum
- The binary XOR of all pile sizes in Nim. A position with nim-sum 0 is a loss for the player to move.
- Overlap method
- In nonograms, shading the cells covered by a block in both its leftmost and rightmost possible positions.
- Pearl
- In Pearl Path (Masyu), a white or black circle that tells the loop to go straight through or turn.
- Pencil marks
- Small notes of candidates in a cell. The games here call them Notes.
- River
- In Nurikabe, the single connected group of shaded cells.
- Run
- In Kakuro, a line of white cells across or down whose digits add up to the clue.
- Sandwich (Hitori)
- A number between two copies of another number in a line; it can never be shaded.
- Straight
- A set of consecutive numbers in any order, such as 5-3-4.
- The 45 rule
- In 9×9 Sudoku variants, every row, column and box adds up to 45.
- Unit
- A row, column or box — any group that must hold each digit once.
- Unique solution
- A well-made logic puzzle has exactly one answer, reachable without guessing.