'electron-deficient' originates from the combination of 'electron' and 'deficient', where 'electron' refers to a subatomic particle with a negative charge, and 'deficient' means lacking or insufficient.

'Electron-deficient' was formed by combining the words 'electron' and 'deficient' to describe a state in chemistry where an atom or molecule lacks electrons.

Initially, it meant 'lacking electrons', and this meaning has remained consistent in modern usage.