Extensibility is defined as the ability of muscle to be stretched back to its original length following contraction.
"Extensibility" is in a different context, as this term is not commonly used in psychology. "Extensibility" typically refers to the ability of a material to be stretched or extended without breaking. In the context of psychology, it is possible that this term could be used metaphorically to refer to the ability of an individual or group to adapt to new situations or challenges without "breaking" or experiencing significant negative outcomes. However, this would be a less common usage and would depend on the specific context and application of the term.