1. A power affecting a person, thing, or course of events, especially one that operates without any direct or apparent effort: Tom's new girlfriend has a very good influence on him, and he is now very considerate and kind to others in comparison to earlier times.
2. Power to sway or to affect someone based on prestige, wealth, ability, or position: Mr. Taylor denies exerting any influence on the citizens to vote for him.

To produce an effect on by imperceptible or intangible means; to sway: Tom's mother tried to influence, or persuade him into studying architecture.