'pyrolytic' originates from Greek/Neo-Latin, specifically the combining form 'pyro-' from Greek 'pyr' meaning 'fire' and the element related to 'lysis' from Greek 'lusis' meaning 'a loosening, a splitting'.

'pyrolytic' developed from the noun 'pyrolysis' (from Greek compounds) and the adjective-forming suffix '-ic' in Neo-Latin/modern scientific English, so 'pyrolysis' → 'pyrolytic' as an adjective describing things related to pyrolysis.

Initially it conveyed the idea of 'splitting or loosening by fire' (literal components), and over time it became the technical adjective meaning 'relating to decomposition by heat' used in chemistry and materials science.