Influential (adjective)

1. Having great influence on someone or something.
2. Having the power to produce an effect or influence others.

Origin:

Mid 17th century: from medieval latin influentia "a flowing in" (in the sense "the power of flowing in", i.e. an astrological influence), from latin influere "flow in".

Examples:

1. The influential politician had a major impact on the country's policies.
2. The influential book sparked a nationwide debate.
3. The influential leader was a role model for many young people.
4. The influential film inspired a new generation of filmmakers.
5. The influential song became an anthem for the youth culture.