What is the meaning of Electro-?

Combining form of electricity.

Combining form of electric and electrical.

Combining form of electronic.

electro-; combining form of elèctric

Superseded spelling of elektro-.

electro-

Pre-reform spelling (used until 1943 in Brazil and 1990 in Portugal) of eletro-. Still used in countries where the agreement hasn't come into effect; may occur as a sporadic misspelling.

electro-

Source: wiktionary.org