microfloppy
/ˈmʌɪkrə(ʊ)ˌflɒpi/Computing
noun
A floppy disk smaller than 51/4 inches (approx. 13.3 cm) in diameter; especially one 31/2 inches (approx. 8.9 cm) in diameter.
Origin
1970s; earliest use found in Electronic Design. From micro- + floppy.