1. Of or relating to or occurring during the time just before menstruation

See also: menstruation

• order Psocoptera
• order Pterosauria
• order Pulmonata
• order Pycnogonida
• order Radiolaria
• order Rajiformes
• order Ranales
• order Ranunculales
• order Raptores
• order Rhamnales
• order Rheiformes
• order Rhoeadales
• order Rhynchocephalia
• order Rickettsiales
• order Rodentia
• order Rosales
• order Rubiales
• order Salicales
• order Salientia
• order Santalales
• order Sapindales
• order Saprolegniales
• order Sarcosporidia
• order Sarraceniales
• order Saurischia