rationalisation n 1: (psychiatry) a defense mechanism by which your true motivation is concealed by explaining your actions and feelings in a way that is not threatening [syn: {rationalization}, {rationalisation}] 2: the cognitive process of making something seem consistent with or based on reason [syn: {rationalization}, {rationalisation}] 3: (mathematics) the simplification of an expression or equation by eliminating radicals without changing the value of the expression or the roots of the equation [syn: {rationalization}, {rationalisation}] 4: the organization of a business according to scientific principles of management in order to increase efficiency [syn: {rationalization}, {rationalisation}] 5: systematic organization; the act of organizing something according to a system or a rationale [syn: {systematization}, {systematisation}, {rationalization}, {rationalisation}]