Is it true that before calling "Portuguese language" the kings of Portugal called their language "Vulgar Latin"?

Answer 1

Yes but VULGAR in that context in those days meant "common?

Answer 2

That is vaguely true. The exact story is: all of the latin languages (Portuguese, Spanish, Italian and French) derive from Latin. Original Latin was for the sophisticated elites and were modified by the everyday citizens who spoke it in their own manner. Therefore, according to geographic location, Latin has transformed into its most colloquial version generating Portuguese in Portugal, Italian in Italy, etc.