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disloyalty (n.)

early 15c., disloialte, from a variant of Old French desloiaute, desleauté "disloyalty, faithlessness, marital infidelity," from desloial, desleal (Modern French déloyal) "treacherous, false, deceitful," from des- (see dis-) + loial (see loyal). Especially of allegiance to a state or sovereign since c. 1600.