'defogger' originates from English, specifically formed from the prefix 'de-' (from Latin, meaning 'remove' or 'reverse') + 'fog' (Middle English 'fogge' meaning 'mist') with the agentive suffix '-er' (indicating an instrument or person).

'defogger' developed from the verb 'defog' (formed by 'de-' + 'fog') with '-er' added to indicate something that performs the action; 'fog' itself comes from Middle English 'fogge' and earlier Germanic roots.

Initially it meant 'something that removes fog or mist,' and it has retained that basic meaning in modern usage, extending from mechanical vehicle devices to sprays and wipes.