1. A condition of lessened reactions to allergens from repeated or prolonged nontherapeutic exposure, similar to hyposensitization. 2. Any procedure in tissue preparation for examinations, such as sectioning for microscopy, that renders the tissue firmer.
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hard·en·ing (hahrґdən-ing) 1. induration (def. 2). 2. sclerosis. 3. the procedure of rendering tissue firm, so that it may be more readily cut for purposes of microscopic examination.Medical dictionary. 2011.