Protractible and Stretchable

Protractible adjective - Able to be extended.

Stretchable and protractible are semantically related in extensible topic. In some cases you can use "Stretchable" instead an adjective "Protractible", when it comes to topics like capable of extension.

Stretchable adjective - Able to revert to original size and shape after being stretched, squeezed, or twisted.

Protractible and stretchable are semantically related in extensible topic. You can use "Protractible" instead an adjective "Stretchable", if it concerns topics such as capable of extension.