Who called Mohammad a "prophet", when?

In which year was Mohammad considered a "prophet"? **Who** first started calling him that? Per dictionary: > **prophet** /ˈprɑfət/ /ˈprɒfɪt/ > > ..future is a foggy mystery, but a prophet sees beyond that fog to speak about what’s to come. A fortune teller is a prophet, and so is a savvy computer designer who knows how technology will change in ten years. Prophet comes from the Greek word for “spokesman,” which explains another definition of prophet: someone who speaks on behalf of God. I disavow this clever use of homonym, for it primaf appears that *someone* is trying to trick the listener into thinking the claim is Mohammad has made prophesies (and if that's the claim, this Q would be Whatever's his prophecy?) putting him at the same level as actual prophets when "Prophet" here merely refers to a spokesman/messenger.In fact the trickery employed here seems to be two-fold, first downgrading Christ to merely-a-prophet and then upgrading Mohammad to the same level. For answer, please kindly include a dictionary quote too [perhaps starting from an arabic one].