- 1. In chemistry, the replacement of an atom or group in a compound by another atom or group ( e.g., s. of H by Cl in CH4 to give CH3Cl). 2. In psychoanalysis, an unconscious defense mechanism by which an unacceptable or unattainable goal, object, or emotion is replaced by one that is more acceptable or attainable; the process is more acute and direct, and less subtle, than sublimation. [L. substitutio, to put in place of another]- generic s. the dispensing of a chemically equivalent, less expensive drug in place of a brand-name product that has an expired patent.- stimulus s. SYN: classical conditioning.- symptom s. an unconscious psychological process by which a repressed impulse is indirectly manifested through a particular symptom, e.g., anxiety, compulsion, depression, hallucination, obsession. SYN: symptom formation.
* * *1) a chemical reaction in which one or more atoms or groups in a molecule are replaced by equivalent atoms or groups to form at least two products esp the replacement of hydrogen in an organic compound by another element or group2 a) the turning from an obstructed desire to another desire whose gratification is socially acceptableb) the turning from an obstructed form of behavior to a different and often more primitive expression of the same tendency <a \substitution neurosis>c) the reacting to each of a set of stimuli by a response prescribed in a key <a \substitution test for speed of learning new responses>
* * *n.2. (symptom substitution) the supposed process whereby removing one psychological symptom leads to another symptom appearing if the basic psychological cause has not been removed. It is controversial whether this happens.
* * *sub·sti·tu·tion (sub″stĭ-tooґshən) 1. the act of putting one thing in the place of another, such as in a substitution reaction. 2. a defense mechanism, operating unconsciously, in which an unattainable or unacceptable goal, emotion, or object is replaced by one that is attainable or acceptable.
Medical dictionary. 2011.