If someone said "dongle" to me today I would assume they mean an adapter of some kind; I've heard it used for the lightning -> audio adapter you need to plug headphones into an iPhone. If I google for "dongle" I see some small USB docks and a few USB=>bluetooth adapters.

I first head "dongle" used to describe the small copy-protection device you needed to plug in to use certain expensive softwares. The software would not launch if it could not detect the dongle.