Literally meaning: “turning the mind or soul”
Origin: Anc Greek
ψυχή/psixhi > ψύχω/psicho (= blow, breath). A psyche in mythology means a butterfly or the soul, spirit, breath and life.
+-τρόπος/tropos(=suffix denoting way, habit, direction, tendency) >τρέπω/trepo(=turn)
In the mid-1950s by American neurophysiologist Ralph Gerard in order to define drugs with an effect on mental activity and behavior.
Any agent that is capable to affect the mind, emotions, and behavior.