hyperextensible

adjective

hy·​per·​ex·​ten·​si·​ble -rik-ˈsten(t)-sə-bəl 

: having the capacity to be hyperextended or stretched to a greater than normal degree

hyperextensible joints

hyperextensible skin

hyperextensibility

-ˈsten(t)-sə-ˈbil-ət-ē 

noun

plural hyperextensibilities