per·mis·sive / pərˈmisiv/ • adj. 1. allowing or characterized by great or excessive freedom of behavior: I was not a permissive parent the permissive society of the 60s and 70s. 2. Law allowed but not obligatory; optional: the Hague Convention was permissive, not mandatory. 3. Biol. allowing a biological or biochemical process to occur: the mutants grow well at the permissive temperature. ∎ allowing the infection and replication of viruses. DERIVATIVES: per·mis·sive·ly adv. per·mis·sive·ness n.