How about Gmaj with diminished 7th?
Or did you mean cord?
You can get an IEC C13 (D-shaped socket) from any electrical or electronics retailer.
Loads on Amazon. I got mine from B&Q Spares (a UK hardware store).
Available in lengths up to around 3m.
If it's a G4 iMac you need the 'cloverleaf' aka 'mickey Mouse' socket IEC C5