He gives it to Malcolm.
his son, Malcolm
Malcolm's title is Prince of Cumberland. He is named Duncan's heir apparent. At the time, the eldest son was NOT automatically the next in line for the throne. Macbeth, as the most experienced and respected soldier, expects to be named, but Duncan passes him over for the feckless Malcolm.
Duncan declares his son, Malcolm, to be Prince of Cumberland, which means that he is the heir to the throne. This proclamation tells the audience that in order for Macbeth to become King, not only does he have to murder Duncan but Malcolm too.
Cumberland County, located in various U.S. states, was named after the Duke of Cumberland, Prince William Augustus, who was the son of King George II of Great Britain. He was notable for his military leadership during the Jacobite rising of 1745. The name reflects the colonial heritage and the influence of British nobility in naming places in America.
Rodney Duncan's birth name is Duncan, Rodney.
Duncan Clyde's birth name is Duncan Watkinson.
King Duncan's full name is Duncan I of Scotland.
Duncan Preston's birth name is Duncan J. Preston.
Duncan Regehr's birth name is Duncan Peter Regehr.
Duncan Sheik's birth name is Sheik, Duncan Scott.
Duncan Staff's birth name is Duncan Dennier Staff.
Duncan McAllister's birth name is Duncan James McAllister.