The property of being permeable. / The rate of flow of a fluid through a porous material. / (geology) A measure of the ability of a rock to transmit fluids (such as oil or water).

(rail transport, Britain, Australia) The track and ballast (bed) of a railway.

In a permanent manner; lastingly. / Forever.

(physics) a measure of the magnetisation of a material in a magnetic field; symbol μ. Materials with values less than 1 are diamagnetic those above are paramagnetic.

Permanently frozen ground, or a specific layer thereof.

Giving permission, or predisposed to give it; lenient. / (of a footpath, bridleway or similar) Open to the public by permission of the landowner. / (biology) That allows the replication of viruses.

(physics) The ratio of magnetic induction to magnetizing force in a vacuum

(physics) A material, or piece of such material, which retains its magnetism even when not subjected to any external magnetic fields.

The movement of a fluid through a porous or permeable solid. / (medicine) The spreading of something (especially something malignant) through the body via blood vessels etc.

(video games, slang) Permanent death, where the player cannot continue but is obliged to restart the game from the beginning.