A "natural deterrent" is something that prevents or discourages something else from happening without using artificial or human-made methods. It happens naturally, without any intervention or control. Full definition
By now most natural health care enthusiasts are aware that Oregano Oil has been clinically shown to be a promising natural deterrent against Viral & Bacterial infections, Hepatitis, Candida, and many other ailments. (bio-alternatives.net)
Cooked Garlic and / or Brewer's Yeast in sensible amounts is safe for dogs and both are a strong natural deterrent to fleas and ticks. (thedogplace.org)
If you've tried blockading them but they still keep coming in, line the doors with natural deterrents such as salt, chalk, curry powder, pepper and cinnamon. (idealhome.co.uk)