what is the most suitable definition of business communication?

Answer 1

Talk.
I'm not trying to be a wise guy.
Your answer's too broad to elicit an intelligent answer.
Phone, e-mail, surface mail, telegram, meeting in an office, on a street corner, at a restaurant, you name it and it's a suitable place if it suits those meeting there.

Answer 2

Clearly unobstructed, easy to understand verbal or print communication transmitted either by in person, by phone and/or electronic media ( Internet / Intranet) for the focused purpose of ensuring productive operations within a business infrastructure, aimed at both client satisfaction and securing / increasing profits.