At least three quantities have been referred to as ‘‘activation energies’’ in association with fits to metastable defect kinetics in hydrogenated amorphous silicon. Most commonly cited isE&tgr;, the activation energy determined from stretched‐exponential fits to kinetics data measured over a range of temperatures. The stretched exponential can also be written in terms of a rate constant,K, which has been reported as being thermally activated. In addition, a stretched‐exponential model describing defect kinetics includes an energy,E2, in its rate equation. In this article, we clarify the interpretations ofE&tgr;,EK, andE2, and discuss the possible physical significance ofE&tgr;.