1. positive stimulus a stimulus with desirable consequences
  2. Eutamius asiaticus terrestrial Siberian squirrel
  3. ultima Thule the geographical region believed by ancient geographers to be the northernmost land in the inhabited world
  4. ultimatum a final peremptory demand
  5. Calamus australis tall scrambling spiny palm of northeastern Queensland, Australia
  6. aversive stimulus any negative stimulus to which an organism will learn to make a response that avoids it
  7. negative stimulus a stimulus with undesirable consequences
  8. alarm system a device that signals the occurrence of some undesirable event
  9. Jatropha stimulosus a stinging herb of tropical America
  10. ultimately as the end result of a succession or process
  11. Ulmus thomasii tall widely distributed elm of eastern North America
  12. altocumulus a cumulus cloud at an intermediate altitude of 2 or 3 miles
  13. conditioned stimulus the stimulus that is the occasion for a conditioned response
  14. ultimateness the state or degree of being ultimate
  15. ecosystem organisms interacting with their physical environment
  16. animosity a feeling of ill will arousing active hostility
  17. epistemology the philosophical theory of knowledge
  18. stimulus any information or event that acts to arouse action
  19. Aulostomus type genus of the Aulostomidae
  20. Tamias striatus small striped semiterrestrial eastern American squirrel with cheek pouches

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