Pioneer (noun)

1. A person who is among the first to explore or settle a new country or area.
2. A person who is among the first to develop, use, or apply a new idea, method, or technology.
3. A person who is first in a field or activity.

Origin:

Late 16th century: from french pionnier, from pion "foot soldier", from piétiner "to tramp", based on latin peditare "to march on foot".

Examples:

1. He is a pioneer in the field of renewable energy.
2. She is a pioneer in the field of women's rights.
3. The pioneers of the American West.
4. He is a pioneer in the field of artificial intelligence.
5. She is a pioneer in the field of space exploration.