from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A puzzle in which a grid consisting of several regions is to be filled with numbers so that every row, column, and region contains only one instance of each number. The most common format is a grid of nine rows and columns that are divided into nine smaller regions of three rows and three columns into which the numbers 1 through 9 must be placed.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A type of puzzle whose completion requires each of typically nine rows and columns and each of as many usually square subregions to contain, without duplication, 1 up to 9 or the grid dimension.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a number puzzle in which the numbers 1 through 9 must be placed into a grid of cells so that each row or column contains only one of each number
Japanese suudoku, contraction of suu(ji wa) doku(shin ni kagiru), the numbers must be unmarried (that is, occur singly).(American Heritage® Dictionary of the English Language, Fourth Edition)
Japanese 数独 (sūdoku), numbers singly (Wiktionary)