[dragonwriter]

They (and their 8" and 5¼" predecessors) were called floppy disks because of the disc of storage media within the outer casing, not because of the casing which was not particularly floppy for the 8” and 5¼” versions, and rather rigid for the 3½” version.

[roywashere]

I thought the 5 1/4s were called floppy disks and the 3 1/2s were called diskettes, at least by the people around me, don’t know if that is a Dutch thing or not

[dragonwriter]

"Type 1 Diskette" was the IBM product description for its first 8-inch one; "floppy disk" was used for the same technology in some places before the first commercially-available products. Both terms were general, neither was specific to any subset of the sizes they would later come in.

There were probably some times and places where local common usage made a distinction between some of the forms then in use by using the two terms differently, though.