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.
Plate tectonics (from the Late Latin tectonicus, from the Greek: ÏÎµÎºÏÎ¿Î½Î¹ÎºÏÏ pertaining to building) is a scientific theory describing the large-scale motion of 7 large plates and the movements of a larger number of smaller plates of the Earth's lithosphere, over the last hundreds of millions of years.