1. Not thought over and arranged systematically in the mind; not absorbed or assimilated mentally
   "an undigested mass of facts gathered at random" 
2. Not digested
   "undigested food"

See also: indigestible, ununderstood

• order Sirenia
• order Solenichthyes
• order Solenogastres
• order Spatangoida
• order Sphaeriales
• order Sphaerocarpales
• order Sphagnales
• order Sphenisciformes
• order Spirochaetales
• order Squamata
• order Stegocephalia
• order Stereospondyli
• order Stomatopoda
• order Strigiformes
• order Struthioniformes
• order Synentognathi
• order Taxales
• order Temnospondyli
• order Testacea
• order Testudinata
• order Testudines
• order Tetraodontiformes
• order Thecodontia
• order Therapsida
• order Thymelaeales