By Mayo Clinic Staff. Erectile dysfunction â the inability to get and keep an erection firm enough for sex â is a common problem. You've likely seen advertisements for erectile dysfunction herbs or supplements to increase your sexual performance..
plate tectonics. In geology, a theory that the Earth's lithosphere (crust and upper mantle) is divided into a number of large, plate-like sections that move as distinct masses. See Notes at fault, Gondwanaland, See more at tectonic boundary.
1 Slab (casting), a length of metal. 2  Slab (geology), that portion of a tectonic plate that is subducting. 3  Slab pull force, the tectonic plate force due to subduction. 4  Slab suction, one of the major plate tectonic driving forces.  Slab window, a gap that forms in a subducted oceanic plate.