rid·dle 1 (rĭd′l)
tr.v. rid·dled, rid·dling, rid·dles
1. To pierce with numerous holes; perforate: riddle a target with bullets.
2. To spread throughout: "Election campaigns have always been riddled with demagogy and worse" (New Republic).
3. To put (gravel, for example) through a coarse sieve.
n.
A coarse sieve, as for gravel.
So I think it's a grader...
