adj

• (chiefly computing) Of a check box: not checked (ticked or enabled).
  "This pseudocode is unambiguous if we know that the previous state of all the boxes is "unchecked." Because we can't be sure of that in buggy code, a better model might be: […]"
• (crosswording) Of a square: part of only one entry (that is, across or down, but not both).
  "If there are W#95;1 "unchecked" whites (that is, those which enter into the solution of one clue only), and W#95;2 "checked" whites (those which enter into the solution of two clues), then the mean word length will be (W#95;1#43;2W#95;2)#47;C, where C is the number of clues. […] Acceptable (if unwelcome) difficulties arise when the initial letters of words occupy unchecked squares, because no hint then derives from other clues as to how that word will start. In six consecutive crossword puzzles in The Times, 16 per cent of the words had unchecked initial letters."