the process of ionizing; the formation of ions by separating atoms or molecules or radicals or by adding or subtracting electrons from atoms by strong electric fields in a gas
the condition of being dissociated into ions (as by heat or radiation or chemical reaction or electrical discharge); "the ionization of a gas"
any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter
(mathematics, logic) such that the arguments or roles can be interchanged; "the arguments of the symmetric relation, `is a sister of,' are interchangeable"
not capable of being distinguished or differentiated; "the two specimens are actually different from each other but the differences are almost indistinguishable"; "the twins were indistinguishable"; "a colorless person quite indistinguishable from the colorless mass of humanity"