To pierce with many holes. The old barn was riddled with bullet holes after the storm of gunfire.
To fill or permeate with something undesirable. The report was riddled with errors and needed a thorough review.
To solve or explain a riddle. He spent the afternoon trying to riddle out the complex puzzle.
To sift or separate (material) using a riddle (sieve). They riddled the sand to obtain a finer grade for the mortar.