Anagrams of: IMPENETRABLE

• allowing fluids or gases to pass or diffuse through

• a preliminary introduction to a statute or constitution (usually explaining its purpose)

• make a preliminary introduction, usually to a formal document

• admitting of penetration or passage into or through

• capable of being penetrated

• a measuring instrument for measuring the area of an irregular plane figure

• capable of being terminated after a designated time

• fit for publication because free of material that is morally or legally objectionable