Candidate
A possible cell where a suspect could be placed, marked before committing to a final position.
Explanation
In harder puzzles, you cannot always place suspects immediately. Instead, you track candidates — the set of cells a suspect could potentially occupy given current constraints. As you gather more clues, candidate sets shrink until only one cell remains.
Example
Cameron might have candidates at (2,3), (2,5), and (4,3). When another suspect is placed at (2,5), Cameron's candidates reduce to (2,3) and (4,3).