This puzzle is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles.
If a word conforms to a special rule, I call it a Numb™ word. Here is a list of Numb™ and not-Numb™ words:
Numb™: Bone, Fur, Mix, Calf, Night, To, Give, Sith, Seen, Sine, Tent, Tree, Hero, Tents
not-Numb™: Bones, Trees, Throne, Cosine, Never, Gonna, Let, You, Down, Rick, Astley
The solution you provide must exhibit relation with the category name of the word, Numb™.