What does it mean to say that Europeans conquered North America?

When we say this, we mean that Europeans came to North
America uninvited and proceeded to take control of the land without the consent of the
Native Americans.  In this way, they can be said to have conquered North
America.

When the Europeans came, the land of North
America, of course, was controlled by the various Native American tribes or nations. 
The Europeans got to North America and wanted to be able to make use of the land.  They
took control of that land through force and through agreements with the Native Americans
that were (many scholars contend) made through deception and
force).

When one group of people comes and takes land that
was previously held by another group, they have conquered that land.  When they force
the people to leave their land, they have conquered the people.  By doing these things,
the Europeans conquered North America.