'pH-agnostic' originates from combining 'pH' and 'agnostic'. 'pH' comes from the notation introduced by Danish chemist Søren P. L. Sørensen (1909), where 'p' denotes 'potentia' (power) and 'H' stands for hydrogen; 'agnostic' comes from Greek 'agnōstos' meaning 'unknown' or 'not known'.

'pH' was introduced as a shorthand for hydrogen ion concentration in 1909 and became standard chemical notation; 'agnostic' entered English in the 19th century (coined by T. H. Huxley) from Greek 'agnōstos'. The compound 'pH-agnostic' is a modern technical coinage, formed by compounding the established technical abbreviation with the adjective 'agnostic' to convey indifference to pH.

Individually, 'pH' denotes a measure of acidity/basicity and 'agnostic' means 'indifferent or not committed'; together they evolved into the technical adjective meaning 'not affected by pH'.