The superlative form of 'seepy', which means something that lets a little bit of liquid through.
This word can make people think of dampness, darkness, and maybe a little bit of fear.
Examples:
This is the seepiest sponge I've ever seen.
The seepiest part of the cave is over there.
The seepiest spot in the house is under the stairs.
The seepiest socks are the ones I left in the rain.
The seepiest place in the whole world is the bottom of the ocean.
The seepiest room in the house is the basement.