The word academic had its origins in the word Academia.   This word came from the Greek term “akademeia” which was a place in Athens that was dedicated to the Goddess of Wisdom.  Later, the world academia came to mean, to other generations of scholars, the collecting of knowledge and transmitting it to new generations of people .  The English came along and tweaked the word to mean a school of higher learner called an academy. Today, the term academic, in England means a researcher who is highly educated, probably holds a Masters or Doctorate and does all kinds of research.  In American the term has come to mean a lecturer, or professor, or a person who is well read, and knows an inordinate amount about one or more subjects. if you use this word as an adjective, it means something that is widely known, or easily known.   Sociologists have a different definition and its more political because to them it means liberal or progressive thought.