This is from the dictionary. While confusing please understand that protocols are at all different levels and exist in hardware and software.
I follow a 'protocol' for designing analog or digital inputs.
I follow a 'protocol' for PCB layout of signals.
I conform to a communications 'protocol' writing code.

How many layers of protocols are there in ethernet?
For serial communications what is not a protocol?
Modem modulation?
Byte size and stop bits?
zmodem or xmodem?

I don't wish to get on anyones case. It is rare that I use the word protocol for hardware but it is not wrong.
Agreement on a lexicon of terms is always my first document when I start a new design.
Without a clear understanding of the words in use you are doomed to failure or at least overtime ;)

For myself, guilty as charged

<From wikipedia>


A communications protocol needs to be specified in such a way that engineers, designers, and in some cases software developers can implement and/or use it. In human-machine systems, its design needs to facilitate routine usage by humans. Protocol layering accomplishes these objectives by dividing the protocol design into a number of smaller parts, each of which performs closely related sub-tasks, and interacts with other layers of the protocol only in a small number of well-defined ways.