| noun | a difficult problem |
| noun | a coarse sieve (as for gravel) |
| verb | pierce with many holes “The bullets riddled his body” |
| verb | set a difficult problem or riddle “riddle me a riddle” |
| verb | separate with a riddle, as grain from chaff |
| verb | spread or diffuse through “An atmosphere of distrust has permeated this administration” |
| verb | speak in riddles |
| verb | explain a riddle |
| riddle | verb | speak in riddles |
| riddle | noun | a difficult problem |
| screen | noun | a strainer for separating lumps from powdered material or grading particles |
| permeative | adjective | spreading or spread throughout |
| permeant | adjective | spreading or spread throughout |
| permeation | noun | the process of permeating or infusing something with a substance |
| pervasive | adjective | spreading or spread throughout |
| pervasion | noun | the process of permeating or infusing something with a substance |
| penetrative | adjective | tending to penetrate; having the power of entering or piercing |
| interpenetration | noun | mutual penetration; diffusion of each through the other |
| diffusive | adjective | spreading by diffusion |
| diffusion | noun | the act of dispersing or diffusing something |
| diffusor | noun | baffle that distributes sound waves evenly |