a nobleman (in various countries) of varying rank
"The king granted hereditary titles to several barons who held significant lands across the kingdom."
a British peer of the lowest rank
"Upon receiving his title, he became a baron, the lowest rank in the British peerage system."
a very wealthy or powerful businessman
"an oil baron"
The male ruler of a barony.
"After centuries of noble service, King Henry granted his loyal knight the title of baron and made him the male ruler of that ancient barony."
In plain English: A baron is an old title for someone who owns land and has special power from their king or queen.
"The local baron owned vast stretches of farmland in the countryside."
A surname.
"The baron was a common family name in that region of England."
The word baron comes from Latin, where it originally meant "to bear." It was used in early Germanic law to describe a man or human being.