'actinologue' originates from Greek, specifically the word 'aktinos,' where 'aktin-' meant 'ray' or 'beam,' and 'logos' meant 'word' or 'study.'

'aktinos' transformed into the French word 'actinologue,' and eventually became the modern English word 'actinologue.'

Initially, it meant 'study of rays,' but over time it evolved into its current meaning of 'a substance that produces a photochemical reaction.'