Psionics is the deliberate use of psychic abilities. These may be sensing abilities (ESP) or abilities that affect matter, or other people (such as Psychokinesis). If you are looking for Psionic Techniques, these may be found in the Grimoire.
The term psionics most likely derives from a science fiction story, in which a telepathic radio was referred to as 'psionic'--combining 'psi' with 'electronic'. Psi is a Greek letter which was used in parapsychological experiments to denote the unknown factor, much as x and y are commonly used to denote variables in mathematics. The term has come into common usage to refer to the use of psychic abilities, rather than specifically to psychically interactive technology, which falls into the category of radionics, psychotronics, or psionic devices.
- Tendency refers to those whose abilities relate to moving thigs, rather than extra-sensory abilities (for whom the term sensitive applies).