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superseded spelling of elektro-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 where the agreement hasn’t come into effect and may occur as a sporadic misspelling

electro-

Source: wiktionary.org