n.1 a the act or an instance of exciting. b the state of being excited; excitement.
2 the action of an organism, tissue, etc., resulting from stimulation.
3 Electr. a the process of applying current to the winding of an electromagnet to produce a magnetic field. b the process of applying a signal voltage to the control electrode of an electron tube or the base of a transistor.
4 Physics the process in which an atom etc. acquires a higher energy state.