Eventually, Malcolm and Angus developed an idea for a band name when their sister Margaret saw the initials on a sewing machine, AC/DC.
The abbreviation means alternating current/direct current electricity, though it has been reported the brother’s felt the name represented the band’s energetic performances.
The brothers formed the band, with their brand-spanking new name, with bassist Larry Van Kriedt, vocalist Dave Evans, and drummer Colin Burgess in November 1973, who they likely met on the Australian band circuit.
Angus quickly began performing in a school uniform-style outfit, which was reportedly an idea of Margaret’s after he tried a variety of other costumes.
source: express.co.uk