a very wealthy or powerful businessman
"an oil baron"
A wealthy and powerful business person.
"The oil tycoon donated millions to build a new university library in his hometown."
In plain English: A tycoon is an extremely wealthy and powerful business leader who controls many companies.
"The tech tycoon donated millions to build new schools in his hometown."
The word "tycoon" comes from Japanese taikun, meaning "great lord," and originally referred to the shōgun. It entered English via Cantonese traders who used it for their powerful leaders, later expanding in modern usage to describe wealthy business magnates or players of simulation games like RollerCoaster Tycoon.