The phrase "periodontal ligament" refers to the tissue that connects the tooth to the surrounding bone. It helps anchor the tooth in its place and allows for minor movement and cushioning during activities like chewing. Full definition
On the left side you can see the bone of the jaw and the blue periodontal ligament. (lbah.com)
The periodontal membrane, or periodontal ligament as it is more properly called, is a ligament just like any other ligament in the body. (sunnysidevetclinic.com)
One of the most enduring theories is that tooth eruption occurs because of the cross-linking and shrinking of the collagen fibers of periodontal ligaments combined with the contraction of the ligaments» fibroblasts. (mypetneedsthat.com)