OPAQUE
| Date | Clue |
|---|---|
| 2016-09-05 | Hard to see through |
| 2014-04-07 | Impossible to see through |
| 2014-03-22 | Hard to grasp |
| 2013-05-10 | Clear as mud, so to speak |
| 2012-10-16 | Impossible to see through |
| 2011-10-30 | Unclear |
| 2010-11-04 | Light-blocking |
| 2009-03-14 | Not easily understood |
| 2003-07-10 | Unclear |
| 2001-06-25 | Opposite of transparent |
| 2001-06-16 | Hard to understand |
| 1999-08-11 | Hard to understand |
| 1998-11-22 | Unclear |
| 1998-11-14 | Muddy |