An Etymological Dictionary of the German Language/Reiter
Reiter, f., ‘coarse sieve, riddle,’ from MidHG. rîter, OHG. rîtara, f., ‘sieve,’ for earlier *hrîtara; corresponding to AS. hrîdder, f., ‘sieve’ whence E. riddle. For the Teut. root hrî in the sense of ‘to sift, winnow,’ see rein. The OHG. suffix tara, from pre-Teut. thrâ (Goth. *hrei-dra, f.), corresponds to -brum for -thrum in Lat. cribrum (br from thr, as in ruber, ἐρυθρός), equiv. to OIr. críathar, ‘sieve’; Aryan kreithro- may be assumed. ModHG. Räder, ‘sieve,’ is not connected with this word.