I say "command line" or "command prompt" when speaking to a Windows-based/minded audience. I drop the 'interface' part as there shouldn't be confusion over it.

I say "command line" or "command prompt" when speaking to a Windows-based/minded audience. I drop the 'interface' part as there shouldn't be confusion over it. I use "terminal" when speaking to a UNIX-based/minded audience. I pronounce it "C-L-I" when thinking to myself.