Pervious

a.
  1. Admitting passage; capable of being penetrated by another body or substance; permeable; as, a pervious soil.
  2. Capable of being penetrated, or seen through, by physical or mental vision.
  3. Capable of penetrating or pervading.
  4. (Zoöl.) Open; -- used synonymously with perforate, as applied to the nostrils or birds.