to do something that is likely to influence someone's attitudes or behavior.

The people in Pennsylvania sent a signal in this election that they wanted health-care reform.

Making polluters pay to recycle old electronics products sends a strong signal to the companies to change the way they do business.

Usage notes: said about actions whether they are intentional or not

• in the catbird seat
• in the clear
• in the closet
• in the cold light of day
• in the cross hairs
• in the dead of night
• in the dead of the night
• in the dead of winter
• in the doghouse
• in the doldrums
• in the driver's seat
• in the dumps
• in the end
• in the event of
• in the event of something
• in the eyes of
• in the eyes of someone
• in the eyes of the law
• in the face of
• in the face of something
• in the family way
• in the fast lane
• in the final analysis
• in the first place
• in the flesh