delocalization
Chemistry term referring to the spreading of electron density over several atoms, as in conjugated systems or resonance structures.
In the benzene ring, delocalization of π electrons contributes to its stability.
共鳴 (resonance) is a concept used to describe delocalization in valence bond theory, while 非局在化 is the more direct term for delocalization itself.
Compound of 非 (non-), 局在 (localization), and 化 (-ization), literally 'de-localization'. A modern scientific coinage.