'pH-stable' originates from modern scientific English as a compound of 'pH' and 'stable'. 'pH' was introduced by Danish chemist Søren P. L. Sørensen in 1909 (the 'p' from German/Latin potenz/potentia meaning 'power' and 'H' for hydrogen), and 'stable' originates from Latin 'stabilis', where the root meant 'standing firm'.

'stable' came into English via Old French and Middle English from Latin 'stabilis'. The notation 'pH' was coined in the early 20th century; the compound 'pH-stable' arose in scientific writing in the 20th century to describe materials or molecules that remain stable across pH ranges.

Originally 'stable' meant 'standing firm' in a physical or figurative sense; in the compound 'pH-stable' the meaning specialized to 'resistant to change when pH varies,' a technical usage that has remained consistent.