1.VerbTo separate (a mixture) into its individual constituents by exploiting differences in some chemical or physical property, such as boiling point, particle size, solubility etc.
"Crude oil is fractionated in a refinery to produce a number of different petroleum products."
2.VerbTo divide a total dose of radiation into fractions.
3.VerbTo divide each plaintext symbol into several ciphertext symbols as a preliminary stage of encryption.
4.VerbTo use the technique of fractionation in hypnosis.