1. The term "Spdf" refers to the labels used to describe the different types of atomic orbitals in chemistry and quantum physics. 2. These letters stand for the shapes of the orbitals where electrons are likely to be found around an atom's nucleus. 3. Specifically, "s" stands for sharp, "p" for principal, "d" for diffuse, and "f" for fundamental. 4. These labels originated from the descriptions of spectral lines observed in atomic emission spectra. 5. Each type of orbital has a different shape and energy level, which helps explain the arrangement of electrons in atoms.