A dictionary definition is not enough to explain what a journalist is, as in dictionary definitions all the shades of the profession go missing, resulting in an insufficient explanation of the role.
However, in the everybody-can-do-everything tech era we must put some boundaries and establish who is liable to do what. Not every person with a camera is a broadcaster, nor every writer is a journalist; sometimes journalists themselves lose track of their role and become copywriters instead.
One could just find the most diverse way to define a journalist.
The emotional response from Time Magazine former editor Henry Antole Grunwald is: “Journalism can never be silent: that is its greatest virtue and its greatest fault. It must speak, and speak immediately, while the echoes of wonder, the claims of triumph and the signs of horror are still in the air.”
Someone else might rather go for the academic definition of Bob Franklin: “Journalism consists in finding things out, then telling people about them via newspapers, radio, television or the internet. […] Journalism helps people understand the world around them and make informed decisions.”
Finally, there are those who opt for the nine-point explanation given by Bill Kovach and Tom Rosentiel:
Journalism’s first obligation is to the truth
Its first loyalty is to citizens
Its essence is a discipline of verification
Its practitioners must maintain an independence from those they cover
It must serve as an independent monitor of power
It must provide a forum for public criticism and compromise
It must strive to make the significant interesting and relevant
It must keep the news comprehensive and proportional
Its practitioners must be allowed to exercise their personal conscience
A journalist needs to know what she or he is doing and why. It can’t be denied that schools, masters and exams might help in this but the best practice is experience. It is not indispensable for journalists to be register somewhere to be recognized for what they are. But they do indeed need to be aware of their role. As for medical profession, journalists make a vow to truth and to the audience.