The term 'thermally-unstable' is derived from the word 'thermal,' which originates from the Greek word 'thermos,' meaning 'hot,' combined with 'unstable,' from Latin 'instabilis,' meaning 'unsteady.'

The concept of 'thermal instability' has been used in scientific contexts since the 19th century, evolving from the study of heat effects on materials.

Initially, it referred to any material that changed with heat, but now it specifically denotes materials that degrade or become hazardous when heated.