Sentence:  Tests to verify the authenticity of <WSD>alicorn</WSD>—most of which involved placing spiders near the horn and observing their reactions—were numerous, but apparently few detected bogus horn, for narwhal tusks, masquerading as unicorn horn, made their way into shops across Europe. 
Meaning of the word marked with <WSD> tags:  The horn of a unicorn considered as a medical or pharmacological ingredient.