1 technical The application of energy to something.
1.1 Physics The process in which an atom or other particle adopts a higher energy state when energy is supplied.
1.2 Physiology The state of enhanced activity of a cell, organism, or tissue which results from its stimulation.
1.3 The application of current to the winding of an electromagnet to produce a magnetic field.
1.4 The application of a signal voltage to the control electrode of an electron tube or the base of a transistor.
2 The action of exciting or the state of being excited; excitement.
Late Middle English: from Old French, from late Latin excitatio(n-), from excitare ‘rouse, call forth’ (see excite).
Andy was excited to observe the excitation of the iron filings on the glass plate above the electromagnet he had made. The filings revealed the presence of the invisible magnetic field.