periderm /perˈi-dûrm/

1. The horny cuticular covering of a hydroid colony
2. The cork cambium with the cork and other tissues derived from it, forming a protective outer covering in plants

peridermˈal adjective

• unforgettable
• unforgettably
• unforgivable
• unforgiven
• unforgiveness
• unforgivenesses
• unforgiving
• unforgivingness
• unforgivingnesses
• unforgot
• unforgotten
• unform
• unformal
• unformalised
• unformalized
• unformatted
• unformed
• unformidable
• unforming
• unforms
• unformulated
• unforsaken
• unforthcoming
• unfortified
• unfortunate