Meaning:
Leader or boss
Example:
David is the commander of the army; he is in charge of all the troops.

3.Pioneer

Meaning:
The first person to do something
Example:
Thomas Edison invented the telephone. He is a pioneer of science.

4. Historic

Meaning:
Something very important that will be remembered for a very long time
Example:
Barack Obama becoming president was very historic, because he was the first black president.

5. License

Meaning:
A small piece of paper or card which says you are allowed to do something
Example:
I just got my driving license, so now I can go on a long road trip.