21 Down

21 Down, in the context of crosswords, refers to the clue pointing to the answer that should be entered into the 21st position in the "down" direction on the crossword grid. Crosswords are puzzles where words are placed into a grid based on numbered clues. "Down" clues indicate that the answers run vertically. Therefore, solving "21 Down" requires finding the word that fits the space allocated for clue number 21 in the downward direction. The number represents the starting square for that word. The length of the word is determined by the number of blank squares following the starting square, intersected by any "across" words.