Actinic rays

Actinic rays, “non-luminous rays of higher frequency than the luminous rays.”

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Actæon * Actinism
Acre, St. Jean d'
Acres, Bob
Acroamatics
Acrolein
Acroliths
Acrop`olis
Acrote`ria
Acta diurna
Acta Sanctorum
Actæon
Actinic rays
Actinism
Actinomycosis
Actium
Acton
Acton, Lord
Acts of the Apostles
Acun`ha, Tristram d'
Acupressure
Acupuncture
Adair, Sir Robert